Price the uncollected sales tax, penalty and interest you have been carrying since the month you crossed a US state's economic nexus threshold.
Threshold test
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Months collecting nothing
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months
Tax you should have collected
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$
Penalty on that tax
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$
Interest accrued to date
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$
Carried today
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$
Six more quiet months add
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$
Still saveable by voluntary disclosure
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$
Keep this run. Export every state you run to .csv for the file, and set dated browser reminders before a lookback window or a quarter closes. Export + reminders — $60 once → $60 once · one licence key per person or team seat · 7-day full refund. A bookkeeper at $75/hour needs about four hours per state to test the threshold and rebuild the year - $300 per state.
Four threshold shapes, not one number States do not share one test. The clock carries the four live shapes - sales only at $100,000, sales or 200 transactions, sales only at $500,000, and sales plus 100 transactions - so a seller picks the shape their state uses instead of trusting a single $100,000 answer. Source: the Streamlined Sales Tax Governing Board remote-seller pages at streamlinedsalestax.org and the state revenue department pages they link, checked 2026-09-21.
Month-by-month accrual, not a flat multiply Tax accrues at the end of each exposed month and interest runs only on the months already gone by, so the oldest month carries the most interest and the newest carries none. That is why a hand calculation of rate times total sales overstates the newest months and understates the oldest.
The price of six more quiet months The same run is repeated six months further out and the difference is shown on its own line, so the cost of postponing registration to the next quarter is a number rather than a feeling.
What a voluntary disclosure still saves A voluntary disclosure agreement normally waives the penalty and limits the lookback to a fixed number of months. The clock prices the penalty plus any tax that falls outside that lookback - the part that stops being saveable the day the state sends its first contact letter.
Your figures never leave the tab Sales, orders and rates are computed in the page. The only outbound call the extension ever makes is licence-key validation to api.polar.sh, which sends the key and nothing else.
Get the complete version $60
This page is the working piece. The full pack has everything below.
Price the uncollected sales tax, penalty and interest you have been carrying since the month you crossed a US state's economic nexus threshold.
A bookkeeper at $75/hour needs about four hours per state to test the threshold and rebuild the year - $300 per state.
You give it the threshold test your state uses, the date you passed it, your average monthly sales into that state and the rate you should have charged. It returns the tax you never collected, the penalty on it, interest accrued month by month, the total you are carrying today, what six more silent months add, and the part a voluntary disclosure can still save.
Who is it for?
US Shopify, Etsy, Amazon and SaaS sellers who ship or sell into states where they have no office, and the bookkeepers and fractional controllers who close their books. It is built for the moment you already know you crossed a threshold and need to tell an owner what the silence has cost so far, in dollars.
Why not just ask a chatbot?
A chatbot will hand you a $100,000 threshold and stop. It does not know the month you crossed, it cannot accrue interest per month on your own figures, and it will happily apply one state's transaction count to a state that dropped transaction counts. The number an owner needs is arithmetic on your numbers, not a remembered threshold.
What is free and what needs the key?
Every calculation is free and unlimited: one state, priced end to end, in the popup or on the web page, with no key and no watermark. The $60 licence key adds two things on a different axis - a .csv export of every state you have run so it can live in the working papers, and dated browser reminders before a lookback window or quarter closes.
What would this cost done by hand?
A bookkeeper at $75 an hour needs roughly four hours per state to rebuild twelve months of sales by destination, test the threshold and build the accrual schedule - about $300 per state, repeated every time an owner asks again. A multi-state nexus study from a state and local tax specialist is quoted well above that.
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