Marketplace Tax Calculator
Work out who collects what when Amazon remits your sales tax — and whether those facilitated sales drag you over a registration threshold you never touched.
Marketplace Tax Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Physical nexus — inventory, employees, offices — attaches at zero sales and is not modelled.
- Threshold measurement windows differ: calendar year, rolling twelve months or preceding quarters.
- Does not track which specific states include or exclude facilitated sales; that is your input.
- Home-rule local jurisdictions in Colorado and Alaska can impose separate registration duties.
In short: A seller with $80,000 of Amazon sales and $25,000 of direct sales into Washington is at $105,000 combined. In a state that counts facilitated sales toward your threshold that crosses $100,000 and you must register — to collect $2,345.00 on direct sales, while the marketplace handles $7,504.00 you never touch.
Formula
Registration and collection are two different questions. Facilitated sales can force you to register in a state where the only tax you then collect is on your own direct channel.
Worked Example
- Separate your channels. $80,000 through Amazon and $25,000 through your own checkout. The platform remits on the first; you are responsible for the second.
- Apply this state's threshold rule. An include state tests $105,000 against $100,000 and you are over. An exclude state tests only the $25,000 of direct sales and you are well under.
- Register if you crossed. Registration brings filing obligations even where the marketplace collects most of the tax. Returns are usually still required, often reporting gross then deducting facilitated sales.
- Collect on your direct channel only. $25,000 × 9.38% = $2,345.00. The marketplace separately remits $7,504.00, which is 76.19% of the total tax on your sales into the state.
- Check the transaction count if the state still has one. At a $25 average order, 200 transactions is $5,000 of sales — 5% of the dollar threshold. That test would have caught you 20 times sooner.
The include/exclude split is the practical trap. The same seller, with the same sales, must register in California and need not register in Oklahoma — purely because California counts marketplace-facilitated sales toward the seller's own threshold and Oklahoma does not. Sellers who assume “Amazon handles it” discover the registration obligation during an audit, by which time the direct-sales tax is uncollected and payable from their own margin.
Strengths & Limits Of This Model
Where this engine is strong
- Models the include/exclude split that decides whether you register at all.
- Separates the registration question from the collection question, which sellers routinely merge.
- Shows where a transaction-count test would have bitten, in revenue terms.
Where it stops
- Cannot confirm whether a specific platform is a facilitator for your product category.
- Does not model return and refund handling, where the collecting party bears the adjustment.
- Assumes one state at a time; a full nexus study needs all fifty run together.
Practical Use Cases
Building a nexus tracker across states
Record the threshold, whether the state includes facilitated sales, and whether a transaction count still applies. Those three fields determine the answer.
Deciding whether to launch your own storefront
Direct sales carry the collection duty that marketplace sales do not. Model the margin impact with the Break Even Calculator.
Preparing for a platform audit
Keep the facilitator’s tax reports. They evidence which sales were covered. Cross-check the rate with the Sales Tax Calculator.
Reviewing registrations after a threshold change
Seventeen states have dropped the transaction test. If you registered only because of a transaction count, you may now be able to deregister — but you must do it formally.
Methodology & Editorial Standards
Every state with a sales tax now has a marketplace facilitator law requiring the platform, rather than the third-party seller, to collect and remit tax on facilitated sales. The obligation attaches to the facilitator once it crosses that state's threshold, counting its own and all third-party sales through the platform, which for any major marketplace is immediate. The question that determines a seller's own position is whether facilitated sales count toward the seller's economic nexus threshold. California Regulation 1684.5 requires sellers to include both direct and facilitated California sales when testing the $500,000 threshold; Oklahoma and several other states exclude facilitated sales from the seller's calculation. Where a seller is pushed over by facilitated volume, registration and filing follow even though the collection duty on those sales sits with the platform, and returns typically report gross sales with a deduction for facilitated amounts. Most states set the threshold at $100,000; California and Texas use $500,000; Alabama and Mississippi use $250,000. As of August 2026 seventeen states have eliminated the 200-transaction alternative, Illinois on 1 January 2026 and Kentucky on 1 August 2026. Connecticut requires both tests to be met, and New York requires $500,000 and more than 100 transactions. Physical presence, including inventory stored in a fulfilment warehouse, creates nexus at zero sales and is outside this engine. The engine implements the standard published formula for this calculation. Inputs are validated for domain and sign before evaluation, and any undefined case returns an em-dash rather than a spurious value.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Marketplace Tax Calculator — 20 Expert FAQs
20 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
Does Amazon collect sales tax for me?
On sales through Amazon, yes, in every state with a facilitator law. On your own website, wholesale or event sales, never — those remain your responsibility.
Do marketplace sales count toward my nexus threshold?
It depends on the state. California includes them under Regulation 1684.5; Oklahoma and Maine exclude them. The same business gets opposite answers.
Why would I register if the marketplace collects the tax?
Because crossing the threshold triggers registration and filing regardless of who collects. You then collect on direct sales and usually report gross with a deduction.
What is the standard economic nexus threshold?
$100,000 in most states. California and Texas use $500,000, Alabama and Mississippi $250,000. New York requires $500,000 and more than 100 transactions.
How many states still use the 200-transaction test?
Fourteen plus Puerto Rico and DC as of August 2026. Seventeen states have removed it and thirteen never had one.
When did Kentucky drop its transaction threshold?
1 August 2026, under House Bill 757. Illinois dropped its own on 1 January 2026, and both now use a $100,000 revenue-only test.
Why are states removing the transaction count?
Because it caught tiny sellers. At a $25 average order, 200 transactions is $5,000 of revenue — the returns cost more to process than the tax collected.
Can I deregister if I only crossed on transaction count?
In states that have repealed the test, usually yes — but you must close the registration formally. Simply stopping collection while registered creates penalties.
Does storing inventory in a warehouse create nexus?
Yes. Physical presence creates nexus at zero sales, so FBA inventory in a state obliges you there regardless of any revenue threshold.
Who handles tax on refunds?
The party that collected it. The marketplace adjusts facilitated sales; you adjust your own. Mismatches here are a common reconciliation error.
Do I still file a return if the marketplace collects everything?
In most states yes, if you are registered. Returns typically report gross sales then deduct facilitated amounts to arrive at taxable sales.
What is Connecticut's rule?
Connecticut requires $100,000 AND 200 transactions — both tests, not either. It is one of the few states where the conjunction works in the seller's favour.
Does the threshold include exempt sales?
In many states yes, gross sales including exempt ones count toward the threshold. Tennessee is explicit that exempt sales count but resale sales do not.
What about income tax on marketplace sales?
Entirely separate. Facilitator laws cover sales tax only; you still report the income, and platforms issue 1099-K forms at the federal reporting threshold.
How often should I re-check my nexus position?
Quarterly. Several states measure on a rolling twelve-month basis assessed each quarter, and thresholds and rules have changed repeatedly through 2025 and 2026.
Is this marketplace tax calculator free to use?
Yes. It is free, requires no account, and has no usage limits. ApexConverter is funded by contextual advertising, never by selling user data.
Is my data sent to a server?
No. The engine runs as Vanilla JavaScript inside your browser under our Zero-Server Client-Side Execution model. Your figures are computed locally and are never transmitted, logged, or stored.
How accurate is this calculator?
It applies the standard closed-form formula in IEEE-754 double precision, rounding only at the display layer. The engine is reconciled against an independent reference implementation before release.
Does it work on mobile?
Yes. The interface is mobile-first with numeric keypad hints and is tested down to a 320-pixel viewport with no horizontal scrolling.
Can I use it offline?
Largely, yes. Because computation is client-side, the page continues to calculate without a network connection once it has loaded.