What to keep for a New York sales tax audit: records, receipts and certificates

Most sales tax trouble at audit time is not about the rate. It is about whether a vendor can show, years later, what was sold, what tax was charged, and why a sale was left untaxed. The Department of Taxation and Finance sets out what it expects in Tax Bulletin TB-ST-770 (recordkeeping) and TB-ST-240 (exemption certificates). This post walks through both and then turns them into one file you could hand over without scrambling.

What the Department says you must keep

This is what the Department's bulletins require. The product suggestions further down are optional.

• Three years, at a minimum. TB-ST-770 says to keep records for a minimum of three years from the return's due date, or from the date you filed if that is later. The Department can require longer, for example during an audit or court case.
• Sales records: invoices, receipts, contracts, guest checks, cash register tapes and other original sales documents. Where no written document is given to a customer, keep a detailed daily record in a daybook or similar journal.
• Purchase records: records showing the taxable status of taxable, resale and exempt purchases.
• Delivery records: if you deliver somewhere other than your place of business, keep proof of where delivery took place.
• Anything else needed to prove the right sales or use tax was collected and paid.

If you sell both taxable and nontaxable items, the bulletin says the invoice or receipt must show which are taxable, and the tax must be stated separately. Exempt sales must be linked to the exemption certificate on file.

Electronic records count the same

Records kept on a computer or point-of-sale system must meet the same requirements as paper and be available to the Department in an electronically readable form, kept in a commonly used format rather than one only proprietary software can open. For POS systems the bulletin lists the detail to capture, including items sold, price, tax, invoice number, date, payment method, and terminal and transaction numbers, and says the audit trail must be operational at all times. If records cannot be tied back to source documents, the Department may use another audit method, such as sampling, and the bulletin lists estimated audits, penalties and interest, and possible suspension of a Certificate of Authority among the consequences of inadequate records.

Exemption certificates: what to hold and what to link

For sales you did not charge tax on, TB-ST-240 is the key document. A complete certificate has the preparation date, purchaser and seller names and addresses, the purchaser's Certificate of Authority number where required, a signature, and the other information the form asks for. The purchaser must give it to you within 90 days of the purchase. You may accept it only in good faith, meaning you had no prior knowledge it was false or fraudulent, and you may refuse any certificate, even a correct one.

On keeping them, the bulletin says to attach the certificate to the record of the purchase or otherwise link it to the sale, and to keep it at least three years from the due date of the return on which the last sale under it was reported. Certificates may be issued and accepted electronically; the bulletin points to TSB-M-07(1)S for details. Certificates from other states or countries are not valid for New York sales tax. Our exemption certificates page explains the individual forms, and our year-end certificate checklist covers refreshing blanket certificates.

Turning that into one audit-ready file

The Department does not prescribe a filing system, so this is one reasonable layout, not an official one.

1. One folder per return period. Label each by the return and its due date, such as the quarter ending November 30, 2026, due December 21, 2026. Because the three years run from the due date, this makes the disposal date easy to compute.
2. Inside it: a copy of the filed return and payment confirmation, the sales summary it came from, and supporting invoices or POS exports.
3. A separate certificates section by customer. File each certificate with the customer's name, the date received, and the sale or invoice numbers it covers. For a blanket certificate, add a note of the last return period reported under it, because that date sets how long it stays.
4. A delivery-proof sleeve for sales shipped or delivered away from your location.
5. A short index sheet at the front listing what is where, so someone else could find it.

Paper filers can do this with a ledger, a binder and page protectors; those who keep everything digitally can mirror the same folders on a drive and keep a second copy. Either way, make sure files open without special software. If you are on paper, a three-ring binder with sheet protectors keeps each customer's certificate flat and visible, and an accordion file organized by month suits the return-period folders. A bookkeeping ledger can serve as the daily record if you issue no written receipts. Look for acid-free or archival paper if you intend to store things for years.

Storing and disposing safely

Records carry customer names, addresses and sometimes tax identification numbers, so store them where they will not be lost or casually read. A fireproof document box protects the originals, and once a period is past its retention date and no audit or dispute is open, a cross-cut shredder is the usual way to dispose of them. Check the Department's retention rule before shredding anything, and do not destroy records tied to an open audit.

Where to find more tools

Our records and bookkeeping supplies page collects the same kinds of items in one place, with the same disclosure. Buying any of them is optional; the Department asks for the records, not for any particular product. This is general information, not tax advice, so confirm requirements for your own business with the New York State Department of Taxation and Finance.