How the IRS Knows About Your Income (Even the Cash You Think They Don't Know About)

A common belief among freelancers: if you did not get a 1099 for it, the IRS does not know about it. This is not how the system works, and the gap between belief and reality is where a lot of people quietly get into trouble.

Here is how income reporting actually works.

The Information Matching Program

The IRS does not just take your word for what you earned. Every 1099-NEC, 1099-K, and W-2 that any employer, platform, or payment processor sends to you also goes directly to the IRS. They receive tens of billions of information returns per year.

The IRS's Automated Underreporter (AUR) program then runs a computer match, comparing what third parties reported paying you against what you reported receiving. Discrepancies generate automated CP2000 notices proposing additional tax.

This is why the CP2000 notice exists. It is not an audit - it is a computer flagging a math discrepancy. No human reviewed your return. An algorithm saw a mismatch and generated a letter.

What Gets Reported to the IRS

1099-NEC. Any business that pays a freelancer $600 or more during 2025 - or $2,000 or more during 2026 and later years, after the One Big Beautiful Bill Act raised the threshold - must file a 1099-NEC and send a copy to both you and the IRS. Every significant client is likely reporting what they paid you.

1099-K. Payment processors (Stripe, PayPal, Venmo, Cash App for Business, Etsy, Amazon, eBay) issue 1099-Ks for accounts meeting the reporting threshold. For 2025 and later, the federal threshold is more than $20,000 in gross payments and more than 200 transactions per processor. Some states require forms at much lower amounts, and processors may issue them voluntarily.

W-2. Your employer reports every dollar of wages.

1099-INT and 1099-DIV. Your bank reports interest. Your brokerage reports dividends.

1099-B. Your brokerage reports every securities sale.

What the IRS Does Not Automatically Know

Cash paid directly by individuals. Private party transactions. Income earned from platforms below the reporting threshold. Tips paid in cash. Sales at garage sales or informal markets.

But "does not automatically know" is not the same as "cannot find out." Bank deposits are visible to the IRS when they investigate. Cash-intensive businesses are a known audit target. Lifestyle inconsistency (spending that does not match reported income) is a flag in examination.

More importantly, the IRS does not need to know about your income for you to owe tax on it. The legal obligation to report all income exists regardless of whether any form was issued. Unreported income is not a gray area - it is a compliance issue.

The 1099-K Threshold Saga and What It Means

The original 1099-K threshold was $20,000 per year AND 200 transactions. The American Rescue Plan Act of 2021 cut it to $600, and the IRS delayed the change repeatedly ($5,000 for 2024 under Notice 2024-85, with $2,500 planned for 2025). In July 2025 the One Big Beautiful Bill Act (Pub. L. 119-21, §70432) repealed the $600 rule retroactively and restored the $20,000/200-transaction threshold for 2025 and later years.

What this means practically. Fewer casual sellers will receive federal 1099-Ks than expected, but the underlying rule never changed: income from selling services, and gains from selling goods, were always taxable. Several states (for example Maryland, Massachusetts, Vermont, Virginia and D.C. at $600; Illinois and New Jersey at $1,000) have their own lower reporting thresholds, so you may still receive a 1099-K well below the federal level. And the IRS still receives 1099-NECs from your clients regardless of any payment platform.

One important nuance: selling used personal items (old furniture, clothes, used equipment) at a loss is generally not taxable income. If you bought a laptop for $2,000 and sold it for $800, that $800 is not income - it is a personal loss (which is also not deductible). Getting a 1099-K for this does not mean you owe tax. It means you may need to show the basis of the item on Form 8949 to explain why it is not taxable.

Why Underreporting Is Riskier Than It Seems

The statute of limitations for the IRS to audit a return is normally three years from the due date. But if you omit more than 25% of gross income, the statute extends to six years. And if the omission is found to be fraudulent, there is no statute of limitations at all.

An underreported 1099 does not just mean taxes owed. It means:

• The original tax plus interest (7% annually for 2025 and most 2026 quarters, compounding daily)
• A 20% accuracy-related penalty if the IRS finds it
• A 25% failure-to-pay penalty if you did not pay what was due
• Potential fraud penalties up to 75% if willful

On a $10,000 underreported 1099 that the IRS finds five years later, the total adds up to roughly $2,500 in tax, $1,000 in interest, $500 in accuracy penalty, and $625 in failure-to-pay penalty. A $4,625 bill on income that would have cost $2,500 if reported honestly.

The Constructive Receipt Rule

Income is taxable when you receive it, even if you choose not to cash the check. This is the constructive receipt doctrine. A check that arrives December 28 is income in the current tax year, even if you do not deposit it until January. A payment credited to your platform account is income when credited, not when you withdraw it.

This matters for year-end timing. Strategies to defer income to the following year require actually deferring receipt, not just depositing late.

The Practical Takeaway

Report all income, even without a form. The legal obligation exists regardless. The matching program catches missing 1099s quickly. Cash income is not invisible - bank records exist and can be subpoenaed. The cost of getting caught vastly exceeds the cost of reporting correctly from the start.

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Sources

• IRS: Information Returns Program - How the IRS matching program works
• IRS: Understanding your Form 1099-K - Current 1099-K thresholds ($20,000 and 200 transactions, restored by Pub. L. 119-21 §70432)
• IRS Quarterly Interest Rates - Interest charged on underpayments
• IRS Publication 17: Your Federal Income Tax - Reporting requirements for all income
• IRS: Statute of Limitations on Audit - 3-year, 6-year, and unlimited windows

All income is taxable regardless of whether a 1099 is issued. Source: IRC § 61. The 25% omission rule extending statute of limitations: IRC § 6501(e).