Do you have to report cash income if you never got a 1099?

Yes. The IRS requires you to report all income you earn, regardless of whether it showed up on any information return, and regardless of how you were paid. Cash, check, Venmo, property, virtual currency: none of it is exempt just because no form was issued. The $2,000 threshold that decides when a payer has to send a 1099-NEC has no bearing on when a recipient has to report the income. Those are two different rules answering two different questions.

Why doesn't the 1099 threshold apply to what you owe?

Because the 1099 threshold is a payer's paperwork obligation, not a taxability test. A client who did $1,500 of side work and never got a 1099-NEC, because the payer's reporting obligation only starts at $2,000 for payments made in 2026 and later, still earned $1,500 of taxable income. The IRS states this directly for gig and side income: it's taxable even when it's "not reported on an information return form" and even when it's "paid in any form, including cash, property, goods, or virtual currency." The absence of a form changes what the IRS was told about the payment. It doesn't change what's owed.

Where does unreported cash income actually go on the return?

Onto Schedule C (Form 1040) if it's business or self-employment income, which is where the IRS directs anyone who operated a business, practiced a profession as a sole proprietor, or did gig work to report it, 1099 or not. Net earnings of $400 or more from self-employment also trigger a filing requirement and Schedule SE self-employment tax, on top of income tax, independent of whether any payer sent a form. Cash tips and occasional payments that don't rise to a trade or business still count as taxable income and generally land as other income on Schedule 1.

What does a preparer do with a client who says "I wasn't paid on paper"?

Treat the absence of a 1099 as missing documentation, not missing income. At intake, ask every self-employed or gig client for their own income record: bank deposits, an invoicing app, a mileage log, a cash log, rather than building the return off whatever 1099s happen to arrive. A client's 1099 packet is a lower bound on what they earned, not the full picture. Plenty of 2026 payments will sit below the new $2,000 threshold and never generate a form at all, and cash jobs rarely generate one regardless of amount. Building a return off "what forms came in" instead of "what the client actually made" is where side income goes missing, and the client owns that exposure whether or not a form ever existed. The threshold that decides whether a form shows up in the first place is its own question: what is the 1099 reporting threshold?