Sales & Use Tax Compliance

    Multi-state sales tax compliance for e-commerce, SaaS, and growing businesses selling across state lines.

    We handle the complexity so you don't have to. Economic nexus analysis, filings, and audit defense in all 50 states.

    • In-house compliance team
    • Multi-jurisdiction experience
    • Secure onboarding
    • Year-round support
    • All 50 states

    Why Sales Tax Gets Complicated Fast

    Selling into more than one state means more than one rulebook, and the obligation usually starts before anyone notices it has.

    Nexus is triggered without a physical presence

    Post-Wayfair economic thresholds mean online sales alone can create a filing obligation in a state you have never visited.

    Every jurisdiction writes its own rules

    Thresholds, taxability of services and digital goods, and filing frequency all differ by state, and some differ by locality.

    Exposure compounds quietly

    Uncollected tax does not disappear. It accrues with penalties and interest until a registration, audit, or acquisition surfaces it.

    What Our Sales Tax Services Include

    From a first nexus review through ongoing filings and audit support.

    Economic nexus analysis

    A state-by-state review of your sales and transaction volume to determine exactly where you have a filing obligation.

    Sales tax registration

    Registration in the states where nexus exists, sequenced to limit lookback exposure where possible.

    Multi-state filing

    Ongoing returns prepared and filed on each state's schedule, with remittances reconciled to your sales records.

    Marketplace facilitator compliance

    Sorting which sales the marketplace already collects on and which remain your responsibility to report.

    SaaS and digital goods taxability

    Taxability determinations for software, subscriptions, and digital products, which vary widely by state.

    E-commerce compliance

    Platform and channel data mapped to jurisdictions so collected tax matches what is actually remitted.

    Sales tax audit defense

    Representation and documentation support when a state opens an audit or issues a notice.

    Voluntary disclosure agreements

    Negotiated disclosure to bring past exposure current, often with reduced lookback and abated penalties.

    The initial nexus conversation is free and takes about 30 minutes.

    Why Sales Tax Is Complex

    Sales tax rules can trip up even experienced business owners. Here's why it matters to get it right.

    Rules vary by state and city

    Each jurisdiction has different rates, rules, and filing requirements. What's taxable in one place may be exempt in another.

    Colorado's unique local structure

    Colorado has home-rule cities and special districts with their own tax rates and filing portals, not just state-level compliance.

    Late filings trigger penalties fast

    Sales tax agencies don't wait. Penalties and interest accrue quickly, and unfiled returns can lead to estimated assessments.

    Proper setup prevents audits

    Getting registered correctly and filing accurately from the start reduces your exposure to audits and surprise bills.

    We make sales tax simple, accurate, and stress-free.

    Sales & Use Tax Services

    Complete sales tax support from registration to ongoing filings, including cleanup, multi-state, and audit defense.

    Sales Tax Registration & Setup

    • New Sales Tax Account Registration

      State and local account setup

    • City and Special District Licensing Guidance

      Home-rule cities and special districts

    • Nexus Determination Support

      Physical and economic presence analysis

    • Multi-Location Sales Tax Setup

      Multiple retail or service locations

    Ongoing Sales Tax Filings

    • Monthly / Quarterly / Annual Sales Tax Returns

      On-time filings every period

    • Accurate Tax Rate Application by Jurisdiction

      Correct rates for every location

    • Colorado Local District Filings

      Denver, Aurora, and home-rule cities

    • Sales Tax Reporting for All Business Types

      Retail, service, and online sellers

    Use Tax Compliance

    • Use Tax Filings for Untaxed Purchases

      Report tax on out-of-state purchases

    • Business Expense Use Tax Review

      Identify unreported use tax exposure

    • Audit Risk Reduction for Use Tax Exposure

      Proactive cleanup and documentation

    Cleanup & Back Filings

    • Catch-Up Sales Tax Returns

      Get current when you're behind

    • Penalty and Interest Minimization Strategy

      Reduce what you owe on back taxes

    • Sales Tax Notice Resolution Support

      Respond to agency letters and notices

    • Historical Filing Corrections

      Amend prior period errors

    Multi-State & E-Commerce Sales Tax

    • Multi-State Sales Tax Compliance Support

      Filing in multiple jurisdictions

    • Marketplace Facilitator Considerations

      Amazon, Etsy, Shopify, and more

    • Sales Tax Collection Strategy for Online Businesses

      When and where to collect

    • Cross-State Registration Roadmap

      Strategic registration planning

    Sales Tax Audit Support

    Every business is different, we confirm your filing obligations and build a compliant process going forward.

    Sales Tax Rules Are Confusing. We Make It Simple.

    Every state has different thresholds, rules, and filing deadlines. Let us figure out exactly where you need to be registered and compliant.

    Economic Nexus & Nexus Analysis

    Wayfair Compliance · Threshold Tracking · Physical & Affiliate Nexus

    Since the 2018 South Dakota v. Wayfair Supreme Court decision, every business selling across state lines faces potential sales tax obligations in 45+ states, regardless of physical presence. Economic nexus has created the single largest compliance burden for e-commerce sellers, SaaS companies, and any business with customers in multiple states. We track your sales against every state's threshold and manage registrations when you cross them.

    Economic Nexus

    Triggered by exceeding a state's sales revenue or transaction count threshold, even without physical presence. Since the 2018 South Dakota v. Wayfair decision, 45+ states have enacted economic nexus laws. Most thresholds are 00K in sales or 200 transactions, but they vary widely. We track your sales against every state's threshold in real-time.

    Real-time threshold monitoring across all states
    Proactive notification before you cross thresholds
    Registration coordination when nexus is triggered
    Retroactive exposure assessment for past-threshold sales

    Physical Nexus

    Traditional nexus based on physical presence: offices, warehouses, employees, inventory, equipment, or even temporary workers in a state. Amazon FBA sellers often have physical nexus in 20+ states because Amazon stores their inventory across its warehouse network. We map your physical footprint to determine all filing obligations.

    Employee and contractor location mapping
    Inventory and warehouse nexus (FBA, 3PL)
    Trade show and temporary presence analysis
    Property and equipment location review

    Affiliate & Click-Through Nexus

    Some states create nexus through affiliate relationships. If you pay commissions to in-state affiliates who refer customers (click-through nexus) or if a related entity has physical presence (affiliate nexus), you may be required to collect sales tax. These rules vary significantly by state and are frequently litigated.

    Affiliate program nexus exposure review
    Click-through referral analysis
    Related entity attribution assessment
    State-by-state affiliate nexus rule tracking

    Economic Nexus Thresholds by State

    StateRevenue ThresholdTransaction ThresholdNotes
    Colorado 00,000 in salesNo transaction thresholdDestination-based sourcing. Home-rule cities have separate thresholds and registrations.
    California$500,000 in salesNo transaction thresholdHighest threshold in the country. District taxes add complexity.
    Texas$500,000 in salesNo transaction thresholdOrigin-based for in-state sellers, destination-based for remote sellers.
    New York$500,000 in sales AND 100 transactions100 transactionsBoth thresholds must be met. Clothing under 10 is exempt.
    Florida 00,000 in salesNo transaction thresholdNo state income tax but aggressive sales tax enforcement.
    Pennsylvania 00,000 in salesNo transaction thresholdDigital goods and SaaS are taxable.
    Washington 00,000 in salesNo transaction thresholdNo income tax, sales tax is their primary revenue source. Aggressive enforcement.
    Illinois 00,000 in sales OR 200 transactions200 transactionsComplex local taxes. Marketplace facilitator rules apply.

    Representative examples. We track all 45+ states with economic nexus laws.

    The Wayfair Timeline

    2018

    South Dakota v. Wayfair

    Supreme Court overturns Quill, allowing states to require sales tax collection from remote sellers based on economic activity alone.

    2019

    Mass adoption begins

    35+ states enact economic nexus laws. Most adopt 00K/200 transaction thresholds modeled on South Dakota's law.

    2020-2021

    Enforcement ramps up

    States begin aggressive enforcement. COVID-driven e-commerce surge pushes millions of sellers past thresholds.

    2022-2024

    Marketplace rules expand

    States expand marketplace facilitator laws and begin auditing non-compliant remote sellers.

    2025+

    Full enforcement era

    States use data analytics, marketplace reporting, and inter-state data sharing to identify non-compliant sellers. Grace periods are over.

    The Grace Period Is Over

    States have moved from education to enforcement. If you've been selling across state lines without collecting sales tax where required, you likely have exposure. We assess your risk, quantify the liability, and evaluate Voluntary Disclosure Agreements (VDAs) to minimize penalties and interest on past-due obligations.

    Marketplace Facilitator Rules

    Amazon · Shopify · Etsy · eBay · Walmart · Social Commerce

    Marketplace facilitator laws now exist in 45+ states, requiring platforms like Amazon and Etsy to collect and remit sales tax on behalf of their sellers. This sounds simple, but the reality is far more complex. Different platforms cover different jurisdictions, direct sales remain your responsibility, and states still expect returns even when the marketplace collected the tax. We help sellers navigate the gap between what marketplaces handle and what falls on you.

    Major Marketplace Coverage

    Amazon

    All 45+ states with sales tax

    Collects and remits on all third-party sales. FBA sellers still need to track inventory nexus for income tax purposes. Amazon provides transaction reports but may not handle all local/district taxes correctly.

    Shopify

    Only collects if you enable Shopify Tax

    Shopify is NOT a marketplace facilitator, you are the seller. Shopify Tax helps with calculations, but you're responsible for registration, collection, filing, and remittance in every state where you have nexus.

    Etsy

    All states with marketplace facilitator laws

    Etsy collects and remits sales tax on orders shipped to states with facilitator laws. Sellers are still responsible for states without these laws and for any direct sales outside Etsy.

    eBay

    All states with marketplace facilitator laws

    eBay collects on facilitator-state orders. Sellers need to track direct sales and non-facilitator states independently. eBay provides 1099-K reporting for qualifying sellers.

    Walmart Marketplace

    All states with marketplace facilitator laws

    Walmart collects and remits on behalf of sellers. However, Walmart does not file returns for you, you may still need to file zero or net-zero returns in registered states.

    TikTok Shop / Social Commerce

    Varies, rapidly evolving

    Social commerce platforms are increasingly subject to facilitator laws, but coverage is inconsistent. Sellers on newer platforms need careful nexus analysis.

    Marketplace Seller Mistakes We Fix

    Assuming the marketplace handles everything

    Marketplaces collect tax on their platform, but if you also sell through your own website, wholesale, or other channels, YOU are responsible for those sales. Many sellers have significant direct-channel exposure they're ignoring.

    Not filing returns in registered states

    Even if a marketplace collects all the tax, some states still require you to file returns reporting those sales, sometimes showing $0 tax due. Failure to file (even zero returns) can result in estimated assessments.

    Ignoring FBA inventory nexus

    Amazon distributes your inventory across multiple warehouses. This creates physical nexus in every state where your inventory sits, not just for sales tax, but potentially for income tax and franchise tax obligations.

    Not tracking marketplace vs. direct sales separately

    Your bookkeeping needs to clearly distinguish marketplace-facilitated sales (where the marketplace collected tax) from direct sales (where you collected tax). Commingling creates filing errors and audit risk.

    Missing local/district tax gaps

    Some marketplace platforms don't collect all local or special district taxes accurately. In states like Colorado (with 70+ home-rule jurisdictions), this creates gaps that you're technically liable for.

    Multi-Channel Sellers Need Special Attention

    If you sell on Amazon AND your own Shopify store AND wholesale, you have three different compliance obligations. Marketplace-collected sales, self-collected sales, and wholesale exemption certificates all need to be tracked separately. We build compliance systems that handle multi-channel complexity cleanly.

    Multi-State Sales Tax Compliance

    Registration · Filing · Sourcing · Exemptions · VDAs

    Multi-state sales tax compliance is the defining challenge of post-Wayfair commerce. With 12,000+ tax jurisdictions, varying sourcing rules, different exemptions, and unique filing portals in every state, managing multi-state compliance internally is a full-time job. We handle the entire lifecycle, from nexus determination through registration, filing, and ongoing monitoring, so you can sell anywhere without compliance risk.

    12,000+

    Tax jurisdictions in the U.S.

    45+

    States with economic nexus laws

    70+

    Colorado home-rule cities

    24

    Streamlined Sales Tax member states

    State-by-State Registration Management

    Each state has its own registration process, filing frequency, and portal. Some states use the Streamlined Sales Tax Registration System (SSTRS), others require individual applications. We manage registrations across all jurisdictions, track renewal dates, and help active permits are maintained.

    SSTRS registration for 24 member states
    Individual state applications for non-SSTRS states
    Local and special district registrations (Colorado home-rule cities)
    Permit renewal tracking and compliance monitoring

    Multi-Jurisdiction Filing

    Filing sales tax returns across 10, 20, or 45 states means managing different due dates, filing frequencies, tax rates, exemptions, and portals. Missing a single filing triggers penalties. We automate tracking and file every return on time, monthly, quarterly, or annually depending on each state's requirements.

    Centralized filing calendar across all states
    Rate and rule changes monitored per jurisdiction
    Automated filing reminders and deadline tracking
    Zero-return filing in low-volume states

    Sourcing Rule Navigation

    Where is a sale 'sourced' for tax purposes? Some states use origin-based sourcing (where the seller is), others use destination-based (where the buyer is). Some use a hybrid. Getting sourcing wrong means collecting the wrong rate, which creates liability in both the over- and under-collected jurisdictions.

    Origin vs. destination sourcing analysis
    Ship-to address validation and rate assignment
    Drop-ship scenarios with three-party transactions
    Digital goods and services sourcing (often different rules)

    Exemption Certificate Management

    Resale certificates, government exemptions, nonprofit exemptions, manufacturing exemptions, each state has different forms, validity periods, and requirements. Accepting an invalid exemption certificate means YOU owe the tax. We build and maintain exemption certificate systems that protect you during audits.

    Certificate collection and validation processes
    Multi-state certificate acceptance rules
    Blanket vs. single-purchase certificate tracking
    Periodic renewal and re-validation programs

    Voluntary Disclosure Agreements (VDAs)

    If you've been selling in states without collecting sales tax, you may have significant back-tax exposure. A Voluntary Disclosure Agreement (VDA) allows you to come forward, register, and typically settle for 3-4 years of back taxes instead of the full statute of limitations, often with reduced or waived penalties.

    Exposure quantification across all non-compliant states
    Anonymous pre-registration inquiries where available
    VDA negotiation and settlement
    Retroactive registration vs. VDA cost-benefit analysis
    Headquartered in Colorado, managing sales tax compliance in all 50 states

    Your Sales Tax Compliance Team

    Our specialists stay current on every state's rules so you don't have to. From nexus analysis to audit defense, we've got your back.

    Management professional at Centennial Accounting Group
    Management
    Tax accountant at Centennial Accounting Group
    Tax Accountant
    Senior accountant at Centennial Accounting Group
    Accountant

    "We treat every client like they're our only client."

    Talk to a Sales Tax Expert

    Sales Tax Audit Defense

    Audit Preparation · Representation · Appeals · Exposure Reduction

    Sales tax audits are increasing as states aggressively pursue revenue from remote sellers, marketplace participants, and businesses with multi-state presence. An audit can go back 3-7 years depending on the state, and assessments of $50K-$500K+ are not uncommon for mid-size businesses. We've represented businesses through hundreds of sales tax audits, and routinely reduce assessed amounts by 40-80% through proper documentation, legal analysis, and negotiation.

    Common Sales Tax Audit Triggers

    Filing late or inconsistently across jurisdictions
    Sudden drops in reported taxable sales without explanation
    Large volume of exemption certificate claims
    High ratio of exempt vs. taxable sales
    Industry-specific targeting (restaurants, construction, e-commerce)
    Cross-referencing with marketplace facilitator data and 1099-K reports
    Nexus present but no registration or filing in the state
    Prior audit history with unresolved findings

    Our Audit Defense Process

    1

    Pre-Audit Preparation

    Before the auditor arrives, we review your records, identify potential exposure areas, organize documentation, and prepare your team for the audit process. Pre-audit preparation routinely reduces assessed amounts by 30-50% compared to going in unprepared.

    Complete sales tax return review for the audit period
    Exemption certificate validation and gap identification
    Taxability analysis for all product and service categories
    Documentation organization and missing record remediation
    Pre-audit exposure estimate and strategy briefing
    2

    Audit Coordination & Representation

    We serve as your primary point of contact with the auditor, managing all information requests, responding to inquiries, and protecting your interests. We attend all audit meetings, review sampling methodologies, and challenge any findings that are overstated or incorrect.

    Direct communication with state/local auditors
    Information request fulfillment and document production
    Sampling methodology review and challenge
    Audit finding analysis and rebuttal preparation
    Settlement negotiation when appropriate
    3

    Post-Audit Resolution

    After audit findings are issued, we review the assessment for errors, negotiate reductions, evaluate protest and appeal options, and implement corrective procedures to prevent future audit exposure. We've successfully reduced assessments by 40-80% through detailed post-audit review.

    Assessment review for calculation and legal errors
    Formal protest and appeal filing when warranted
    Penalty abatement and interest reduction requests
    Payment plan negotiation for remaining liability
    Process improvements to prevent recurrence

    Top Audit Exposure Areas

    Taxability Misclassification

    You've been treating certain products or services as exempt when they're actually taxable (or vice versa). This is the most common audit finding and often results from applying the wrong state's rules or relying on outdated guidance.

    Use Tax Non-Compliance

    Your business purchased equipment, software, supplies, or services from out-of-state vendors who didn't charge sales tax. You owe use tax on these purchases. Auditors pull your expense records and cross-reference against use tax filings, this is low-hanging fruit.

    Exemption Certificate Deficiency

    You accepted exemption certificates from customers but the certificates are expired, incomplete, or invalid for the jurisdiction. Without a valid certificate, you owe the tax, even if the customer was legitimately exempt.

    Sourcing Errors

    You've been charging tax based on your location (origin-based) when the state requires destination-based sourcing, or vice versa. This creates simultaneous over-collection in some jurisdictions and under-collection in others.

    SaaS & Digital Goods Taxability

    SaaS · Digital Downloads · Cloud Services · Information Services

    SaaS and digital product taxability is the fastest-evolving area of sales tax law. With no federal framework and states taking wildly different positions, a single SaaS product can be taxable in 23 states, exempt in 20, and unclear in the rest. As states look for revenue from the digital economy, more are expanding their definitions to capture SaaS, cloud services, and digital goods. We help technology companies navigate this complexity, from taxability determination through multi-state compliance.

    Digital Product Tax Categories

    SaaS (Software as a Service)

    ~23 states tax SaaS

    Examples: CRM tools, project management, accounting software, design tools

    Some states tax SaaS as tangible personal property, others as a service, others exempt it entirely. The same product can be taxable in Texas but exempt in California.

    Digital Goods (Downloads)

    ~30+ states tax digital goods

    Examples: E-books, music downloads, digital art, templates, courses

    States vary on whether digital goods are taxable, some only tax if there's a tangible equivalent. Streaming vs. download distinction matters in some jurisdictions.

    Cloud Infrastructure (IaaS/PaaS)

    ~10-15 states tax cloud infrastructure

    Examples: AWS, Azure, Google Cloud, Heroku, database hosting

    Most states exempt cloud infrastructure, but some (like Texas and Pennsylvania) treat it as taxable data processing. Multi-state cloud usage creates complex sourcing questions.

    Digital Advertising

    Limited, but growing

    Examples: Google Ads, Facebook Ads, programmatic advertising

    Maryland enacted the first digital advertising tax. Other states are considering similar legislation. This is an emerging and rapidly evolving area.

    Information Services

    ~15-20 states tax information services

    Examples: Data subscriptions, market research, credit reports, API access

    States define 'information services' differently. Some exempt custom reports while taxing canned data. The line between SaaS and information service varies by jurisdiction.

    SaaS Tax Complexities

    Bundling & Unbundling

    When SaaS products include taxable and non-taxable components (e.g., software + consulting + training), states have different bundling rules. Some tax the entire invoice if any component is taxable ('true object test'). Others allow unbundling if separately stated. Proper invoice structuring can save significant tax.

    B2B vs. B2C Treatment

    Some states exempt SaaS sold for business use (B2B) while taxing consumer purchases (B2C). Others make no distinction. If you sell to both, you need a system that applies the correct tax treatment based on the buyer's use, not just their entity type.

    Reseller & Wholesale Exemptions

    SaaS companies that sell through channel partners or resellers need to manage exemption certificates for wholesale transactions. If a reseller is bundling your SaaS into their taxable product, different rules may apply.

    International Considerations

    SaaS companies selling internationally face VAT/GST obligations in addition to U.S. sales tax. The EU, UK, Canada, and Australia all have digital service tax rules. We coordinate domestic sales tax with international indirect tax obligations.

    The Landscape Is Shifting

    States are actively expanding their sales tax base to include more digital products and services. What was exempt last year may be taxable this year. We monitor legislative changes across all jurisdictions and proactively notify clients when new taxability rules affect their products. Waiting for an audit to discover you should have been collecting is an expensive mistake.

    E-Commerce Sales Tax Compliance

    Shopify · Amazon · WooCommerce · Multi-Platform Sellers

    E-commerce sales tax is not optional. If you're selling online and exceeding economic nexus thresholds, which most growing e-commerce businesses do in multiple states, you're required to collect, report, and remit sales tax in every state where you have nexus. The complexity multiplies with every platform, product category, and state you sell in. We build compliant e-commerce tax systems from the ground up and manage ongoing compliance so you can focus on growth.

    Platform-Specific Tax Challenges

    Shopify

    Shopify Tax calculates but does NOT file returns, you're fully responsible
    Product taxability configuration requires manual setup per product category
    Third-party apps (TaxJar, Avalara) add automation but need proper configuration
    Shopify POS for retail adds additional local tax complexity

    WooCommerce / WordPress

    No built-in tax calculation, relies entirely on plugins or manual rates
    Tax table imports need regular updates as rates change
    Plugin conflicts can silently break tax calculations
    Custom product types may not integrate with tax automation tools

    Amazon FBA

    Amazon collects marketplace-facilitated tax but creates physical nexus via inventory distribution
    FBA inventory in 20+ states creates income tax and franchise tax exposure beyond sales tax
    Commingled inventory makes nexus analysis more complex
    Amazon's tax reports don't always match your accounting records

    BigCommerce / Squarespace / Wix

    Built-in tax features vary significantly in accuracy and coverage
    Limited support for complex scenarios (digital goods, services, subscriptions)
    Integration with third-party tax engines may be limited
    Multi-location inventory not always supported natively

    E-Commerce Tax Compliance Checklist

    Nexus Determination

    Map all states where you have economic nexus (sales volume)
    Identify physical nexus from inventory, employees, or trade shows
    Track marketplace vs. direct sales by state
    Monitor threshold changes as states update their rules

    Tax Collection Setup

    Register for sales tax permits in all nexus states
    Configure tax calculation on your e-commerce platform
    Set product taxability codes for all SKUs
    Test checkout tax calculations for accuracy

    Filing & Remittance

    Establish filing frequency in each state (monthly/quarterly/annual)
    Reconcile marketplace-collected vs. self-collected tax
    File returns and remit payments on time in every jurisdiction
    Maintain filing calendar with all due dates

    Ongoing Compliance

    Review new nexus thresholds quarterly
    Update product taxability as laws change
    Manage exemption certificates for wholesale/resale customers
    Reconcile sales tax collected vs. reported on returns

    Growing Fast? Plan Ahead.

    Every new state you start selling in is a potential new filing obligation. We monitor your sales volume against every state's nexus threshold and register you proactively, before the state sends a notice. Growth is great. Surprise tax assessments are not.

    Selling Online? You Might Have Nexus in More States Than You Think.

    Post-Wayfair rules mean more obligations than ever. Let us audit your exposure, it's free and takes less than 30 minutes.

    Who We Help

    If you collect sales tax, or should be, we'll help you stay compliant.

    Retail Stores & Boutiques

    In-store sales, multiple locations, local compliance

    E-Commerce Sellers

    Online sales, marketplace considerations, multi-state nexus

    Contractors with Taxable Materials

    Material purchases, job site locations, use tax

    Restaurants & Hospitality

    Food and beverage sales, delivery, catering

    Service Businesses with Multi-City Exposure

    Services performed in multiple jurisdictions

    Multi-State Companies

    Economic nexus, remote sales, cross-border compliance

    How Sales Tax Compliance Works

    A clear process to get you registered, filing, and staying compliant.

    1

    Review Filing Requirements + Registrations

    We assess where you need to register and what returns are required based on your sales activity.

    2

    Prepare and File Returns On-Time

    Accurate calculations, proper jurisdictions, and timely submissions every filing period.

    3

    Ongoing Support + Notice Resolution

    We stay with you, handling notices, answering questions, and adjusting as your business grows.

    Most clients can be stabilized within 30 days, even if filings are behind.

    How Sales Tax Compliance Works With Us

    Four steps from a nexus review to filings that stay on schedule.
    1. Step 1

      Schedule a free consultation

      Tell us where you sell, what you sell, and which platforms you use. Roughly 30 minutes.

    2. Step 2

      Review your current exposure

      We run a nexus review against your sales data to identify states where registration is already required.

    3. Step 3

      Receive a tailored compliance plan

      Registration sequence, filing calendar, and any disclosure recommendations, with the fee confirmed up front.

    4. Step 4

      Ongoing filing and support

      Returns filed on each state's cadence, with monitoring as new thresholds are crossed.

    Earlier reviews usually mean smaller lookback exposure.

    Why Businesses Choose Us for Sales Tax

    Rules tracked for you

    State thresholds and taxability rules change constantly. Following them is our job, not an item on your list.

    Built for online sellers

    E-commerce, SaaS, and marketplace sellers make up the core of this practice rather than an occasional case.

    Exposure handled honestly

    Where past exposure exists, we map it and present the disclosure options rather than registering and hoping.

    Tied to your books

    Filings pull from the same records our accounting team maintains, so remittances reconcile to recorded sales.

    What Clients Say

    "Centennial Accounting Group is always very professional and very knowledgeable. I would highly recommend them if you are looking for any financial services."
    Abod AliOwner, Denver Car Choice

    Nexus reviews, registrations, and filings are handled by our in-house Denver compliance team, working from the same records our accounting group maintains.

    Read more client reviews

    Be Prepared

    What You'll Need for Sales Tax Compliance

    The more data we have, the faster we can assess your nexus exposure and build a compliance plan. Gather what you can, we'll identify gaps.

    Sales & Revenue Data

    • Monthly sales reports by state (POS, Shopify, Amazon, etc.)
    • Marketplace settlement reports (Amazon, Etsy, eBay, Walmart)
    • Direct-channel sales data by shipping destination
    • Wholesale vs. retail revenue breakdown
    • Digital product and subscription revenue by state
    • Refund and return records

    Registration & Compliance Records

    • Current sales tax permit numbers and registration states
    • Business license details for each jurisdiction
    • Prior filed sales tax returns (all states)
    • Any notices or correspondence from tax agencies
    • Exemption certificates received from customers
    • Voluntary Disclosure Agreement history (if any)

    Business Operations

    • List of states where you have employees or contractors
    • Warehouse, inventory, and fulfillment center locations
    • Trade show or event attendance by state
    • Affiliate program details and commission payments
    • E-commerce platform(s) and tax configuration
    • Product/service catalog with taxability classifications

    Financial Context

    • Year-to-date P&L and balance sheet
    • Use tax payments made on out-of-state purchases
    • Equipment and supply purchases from out-of-state vendors
    • Sales tax collected vs. remitted reconciliation
    • Prior audit findings or assessment notices
    • Bookkeeping system access (QuickBooks, Xero, etc.)

    Don't have everything?

    Most clients don't have every item ready, that's normal. We send a customized checklist based on your specific situation. The most critical items are your sales data by state and current registrations. We can work with what's available and build from there.

    Schedule Your Free Consultation

    Sales Tax FAQs

    Everything you need to know about sales tax nexus, multi-state compliance, SaaS taxability, audit defense, and e-commerce obligations.

    Stop Guessing. Get Compliant.

    Multi-state sales tax compliance, nexus analysis, and audit defense from a team that does this every day.

    Book Free Sales Tax ConsultationCall (720) 603-9700
    Headquartered in Denver, CO, managing sales tax compliance in all 50 states

    Important disclosure about government services

    Centennial Accounting Group is a private accounting firm, not a government agency, and is not affiliated with or endorsed by the Colorado Department of Revenue or any local taxing jurisdiction. Sales tax licenses and returns can be filed directly with those agencies at no charge beyond the agency's own fees. Our fees are for our professional registration support, filing, and advisory services only.

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