New York Sales Tax Statute of Limitations: Three-Year Rule, Exceptions

The New York sales tax statute of limitations gives the Department of Taxation and Finance three years from the date you file a sales tax return to assess additional tax for that period. That baseline sits in Tax Law Section 1147(b). It disappears entirely if you never filed a return, filed a fraudulent one, or accepted a fraudulent exemption certificate, and it can be extended by written agreement during an audit.¹

When the Three-Year Clock Starts

The clock runs from the day you file, with one wrinkle. File early and the three years still doesn’t begin until the return’s actual due date. A quarterly return due March 20 but submitted March 10 is treated as filed on March 20, so the assessment window closes March 20 three years later.¹

Once that period expires, the tax period is effectively closed. A Notice of Determination mailed after the deadline can be challenged as time-barred. The state has to postmark the notice within the window; late by even a day and it loses its legal authority to collect the deficiency for that period.²

The Postmark Controls

Section 1147(a)(2) sets a mailbox rule: the U.S. postmark on the envelope is treated as the delivery date, whether you’re mailing a return to the Department or the Department is mailing a notice to you. Registered or certified mail creates a legal presumption of delivery.¹

A change to U.S. Postal Service processing that took effect in late 2025 complicates the practical side. Postmarks are now applied when mail reaches automated processing rather than when USPS first takes possession. That gap can run one to three days for items dropped in collection boxes or originating far from a regional processing center. For anything time-sensitive going to the Department, certified mail or a manual counter postmark protects the date. Electronic filing avoids the issue.

When the Time Limit Does Not Apply

Three situations remove the statute of limitations completely and give the Department unlimited time to assess:

No return filed. If you never submitted a required sales tax return, the three-year clock never starts. The Department can assess tax, penalties, and interest for periods going back a decade or more, with no outer boundary.
Fraudulent return. A willfully false or fraudulent return filed with intent to evade tax removes the time limit permanently for that period.
False exemption certificate. If a purchaser gives a vendor a fraudulent resale or exemption certificate to avoid tax, the Department can assess the tax against that purchaser at any time.

All three exceptions live in Section 1147(b) itself.¹ The exemption certificate exception matters more than businesses often realize, because resale certificates get treated as routine paperwork. If the Department later determines a buyer used a bogus certificate, the buyer, not the vendor, faces the open-ended assessment.

Fraud has to be proven, and an honest mistake is not fraud. A transposed number on a return is a correction. Systematically underreporting cash sales for years is another matter. The Department carries the burden, but once it establishes fraud, the protective three-year window vanishes retroactively for every period affected.²

Consent Agreements That Push the Deadline Out

When the Department can’t finish an audit before the three-year window closes, it will ask you to sign a written consent extending the assessment period. Section 1147(c) allows this, and multiple extensions are permitted so long as each new consent is signed before the prior one expires.¹

The Department typically uses Form AU-7, Consent to Extend the Time to Assess Sales and Use Tax. The form specifies a new expiration date that both sides agree to, and that date becomes the new legal boundary for issuing an assessment.

You are not required to sign. Refusing has practical consequences. If the Department sees the clock running out and cannot finish its review, it will issue an estimated assessment under Section 1138 to protect its position before the deadline. Estimated assessments are built on whatever information the Department has and tend to run high. Many taxpayers find that agreeing to an extension produces a smaller bill than fighting the clock and getting hit with an estimate built on assumptions.³

Signing a consent has a benefit that cuts the other way as well. If you agree to extend the assessment period, your deadline to file for a refund or credit under Section 1139 doesn’t expire until at least six months after the extended assessment period ends.¹

Refund Claims Run the Other Way

The statute of limitations works in both directions. You have your own window to recover overpayments, set by Section 1139, and the rules differ depending on how the tax was paid.

If you overpaid through a vendor, you must file a refund application within three years of the date that vendor was required to remit the tax to the Department. If you paid the tax directly, you have three years from the date the payment was due. Either way, the refund is limited to the tax paid within the three years before you filed the claim.⁴

An alternative two-year window runs from the date you actually paid the tax. You get whichever period expires later. If you rely on the two-year period, the refund is capped at what you paid during those two years. If no return was filed at all, only the two-year period applies.⁴

Businesses that discover they’ve been overtaxing transactions, such as collecting tax on items that turned out to be exempt, need to move quickly. The three-year clock runs whether you know about the overpayment or not.

Ninety Days to Challenge a Notice of Determination

Even a timely assessment can be beaten on procedure if you miss the response deadline. When the Department mails a Notice of Determination, whether from an audit or an estimate, you have 90 days from the mailing date to petition the Division of Tax Appeals for a hearing. If you are outside the United States, that window extends to 150 days. Miss the deadline and the notice automatically becomes a final assessment, and collection begins.³

The 90-day clock is strict. The date on the certified mail receipt controls, not the date you opened the envelope or the date your accountant first looked at it. Count forward from the mailing date.

Records to Keep While the Clock Is Running

Section 1135 requires every person collecting sales tax to keep records of every sale, the tax collected, and documentation supporting exempt transactions, including sales slips, invoices, and receipts.⁵ The Department’s published guidance sets a minimum retention period of three years from the due date of the return the records relate to, or from the date the return was actually filed, whichever is later.⁶

Sign a consent extending the assessment period and your record retention obligation extends with it. You need documentation covering every period still open to audit. Destroying records while an extended window is still running is the fastest way to end up facing an estimated assessment built entirely on the Department’s assumptions.

Three years is a floor, not a ceiling. If you have unfiled returns, open audit issues, or periods where fraud might be alleged, keep everything until the matter is fully resolved. Records you can produce are the real defense against an estimate, and once they are gone, the Department’s number becomes very hard to move.

1
New York State Senate. New York Tax Law 1147 – Notices and Limitations of Time
2
New York Codes, Rules and Regulations. 20 CRR-NY 535.3 – Limitation of Assessment
3
New York State Senate. New York Tax Law 1138 – Determination of Tax
4
New York State Senate. New York Tax Law 1139 – Refunds
5
New York State Senate. New York Tax Law 1135 – Records to Be Kept
6
New York State Department of Taxation and Finance. Recordkeeping Requirements for Sales Tax Vendors