Idaho Sales Tax Form 850: Filing, Due Dates, and Use Tax

Idaho sales tax Form 850 is the Sales and Use Tax Return that every holder of an Idaho seller’s permit files with the Idaho State Tax Commission to report total sales, subtract nontaxable transactions, calculate tax at the state’s 6% rate, and remit payment. Most retailers file it monthly, and the return and payment are due by the 20th of the month after the reporting period.¹

What Form 850 Reports

The return walks through a short calculation. Line one is total sales for the period, including cash and credit transactions even if payment hasn’t arrived. That figure covers sales originating in Idaho, sales originating in Idaho but shipped out of state, and sales originating out of state but delivered into Idaho.²

The next line subtracts nontaxable sales. Idaho treats these categories as nontaxable: sales shipped or delivered outside the state, sales to exempt entities, wholesale sales, and repair labor.² Total sales minus nontaxable sales gives you net taxable sales, and that figure gets multiplied by the tax rate.

Two categories stay off the return entirely: lodging sales already reported on your behalf by a short-term rental marketplace, and sales that a marketplace facilitator reported and remitted for you. Reporting them again would double-count.

A separate line captures use tax on items your business bought without paying Idaho sales tax. There’s also an adjustments line, but any adjustment requires a written letter explaining the reason, and the Tax Commission can reject it. Prior payments do not go on the adjustments line.²

Two checkboxes at the top handle administrative changes. One updates your mailing address. The other, labeled “Cancel Permit,” signals a final return because the business has closed; if you check it, include the date operations stopped.

Filing Frequency and Due Dates

How often you file depends on how much tax you collect. The default is monthly, with each return and payment due by the 20th of the following month. When the 20th falls on a weekend or holiday, the deadline moves to the next business day.¹

Retailers who collect $750 or less in tax per quarter and have a clean filing history can request quarterly filing, with returns due within 20 days after the quarter ends.¹ Distributors and wholesalers with limited retail activity can apply to file semiannually (due July 20 and January 20) or annually (due January 20). Annual filing is generally limited to seasonal operations like Christmas tree lots or recurring fair vendors.³

File even when you had no sales. Skipping a return because nothing happened is treated the same as a late filing.¹

How to File Form 850

Filing runs through the Taxpayer Access Point, known as TAP. The Tax Commission no longer mails paper returns.¹ You log in, enter your figures, and submit the return and payment through the same portal. Temporary seller’s permits also file through TAP.

Because paper returns aren’t distributed, set up a TAP account well before your first deadline. The system is reached through the Tax Commission’s website at tax.idaho.gov.⁴

Use Tax on the Same Return

Form 850 isn’t only about sales you make. It also captures use tax on items your business bought without paying Idaho sales tax. That typically happens with online purchases from sellers who don’t collect Idaho tax, or items pulled from resale inventory for your own business use.²

Use tax runs at the same rate as sales tax and applies whenever you store, use, or consume tangible goods in Idaho that escaped sales tax at purchase.⁵ Many businesses track it with a use-tax accrual account or a worksheet listing each untaxed purchase. Keep those records for at least four years if you hold a use tax permit, or seven years if you don’t.

Penalties and Interest for Late Filing

Idaho applies two separate penalty structures. If you file on time but don’t pay in full, the penalty is 0.5% of the unpaid tax per month, capped at 25%. If you fail to file the return at all, the penalty jumps to 5% of the tax due per month, also capped at 25%.⁶ Either way, the minimum penalty is $10.²

Interest accrues on unpaid tax from the original due date until paid in full. The annual rate is 2% plus the midterm federal rate published by the U.S. Treasury each September, rounded to the nearest whole number.⁷ For 2025, that rate was 6%. So a zero-sales return filed on time costs nothing, while forgetting to file one can still generate penalties even when no tax was owed.

Local Sales Taxes in Resort Cities

Some Idaho resort cities add a local sales tax on top of the state’s 6%. These are voter-approved, and each city sets what it taxes. Some apply the local rate to everything subject to state sales tax; others limit it to lodging, restaurant food, and alcoholic drinks served by the glass.⁸ If your business operates in a resort city, check the Tax Commission’s local tax page for the rate and taxable categories that apply, and report the local tax on the same Form 850 filing.

What Form 850 Does Not Handle

Changes to your business structure, ownership, partners, officers, or physical address are not reported on Form 850. Those go through Form IBR-1 or the online portal at tax.idaho.gov/ibr.² The one exception is a mailing address change, which you can note directly on Form 850 with the checkbox at the top. Adding new locations, restructuring ownership, or converting from a sole proprietorship to an LLC all go through the separate registration process.

1
Idaho State Tax Commission. Sales Tax Filing and Paying
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Idaho State Tax Commission. Form 850 Instructions – Sales and Use Tax Return
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Legal Information Institute. Idaho Admin Code r 35.01.02.105 – Returns
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Idaho State Tax Commission. TAP Introduction and Registering
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Idaho State Tax Commission. Use Tax Basics Guide
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Idaho State Legislature. Idaho Code 63-3046 – Penalties
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Idaho State Legislature. Idaho Code 63-3045 – Notice of Deficiency
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Idaho State Tax Commission. City Sales Taxes