If you take a business deduction, you have the burden of proof. The IRS says you must be able to prove the entries and deductions on your return (Topic 305). A bank line that says “Amazon $84” is not enough by itself — supporting documents should show who you paid, how much, when, and that it was a business expense (What kind of records should I keep).
What to keep
For ordinary expenses: receipt, invoice, or canceled check / card statement — often a combination — that identifies the payee, amount, date, and a description that shows it was business (same IRS page). For travel, meals, gifts, and car, Pub 463 asks for more: time, place, amount, and business purpose, kept close to when the expense happened.
How long
Usually 3 years from when you filed (or the due date if you filed early). 6 years if you omit more than 25% of gross income. 7 years for a bad-debt or worthless-securities claim. Keep property records until you dispose of the asset plus the normal period. Employment-tax records: at least 4 years. If you never filed, or filed a fraudulent return, keep records indefinitely (How long should I keep records).
Not legal advice. Your facts differ. Talk to your accountant.
FAQ
- Card statement enough? Often not alone. Pair it with the itemized receipt.
- Paper required? The IRS does not require a special bookkeeping method, but you must clearly show income and expenses (Topic 305). Ask your accountant if a photo + CSV is enough for them.
Not legal advice. Talk to your accountant.