When Is the IRS Finally Out of Time to Audit You?

Here’s a question I hear pretty often: “How far back can the IRS go?”

The honest answer is: it depends. For most people with clean returns, the answer is three years. For people who underreported income significantly, six years. For people who committed fraud or never filed at all — forever. No time limit.

Understanding which category you’re in matters. Especially if you’ve ever had a year with complicated income, a missed form, or a business that’s been through some changes.

The Standard Rule: Three Years

The IRS has three years from the later of two dates to assess additional tax: the return’s due date, or the date you actually filed — whichever is later.

So if you filed your 2023 return on April 15, 2024, the IRS generally has until April 15, 2027 to open an audit on that return. If you filed an extension and submitted on October 15, 2024, the window runs to October 15, 2027.

Three years is the baseline. Most routine audits happen well within this window. The IRS’s automated systems flag returns within the first year or two. A correspondence audit — the most common kind — typically kicks off within eighteen months of filing.

The Six-Year Exception

Here’s where it gets more important for business owners.

If you omit more than 25% of your gross income from a return, the statute of limitations extends to six years. This isn’t about a small rounding error. It’s about a substantial understatement — a number that materially changes what you reported.

The most common triggers:

• Income from a side business or secondary revenue stream that didn’t make it onto the return
• Cash income that wasn’t reported — especially relevant for service businesses, construction, home services
• 1099 income that you forgot about or didn’t receive (the IRS matches their copies against your return — they know)
• K-1 income from a partnership or S-corp that didn’t get reported on the personal return

If you underreport by 25% or more, the IRS has six years, not three. That means a 2021 return filed in April 2022 could remain open for audit until April 2028 if the gross income was substantially understated.

Schedule C filers — sole proprietors — get more scrutiny than almost anyone else, and the six-year extension is more likely to apply when income is harder to verify. The audit dynamics for Schedule C vs. S-corp are worth understanding.

No Limit: When the Clock Never Starts

Two situations remove the statute of limitations entirely.

You never filed the return. If there’s no return, the clock never starts. There’s no filing to trigger the three-year window. The IRS can assess tax, penalties, and interest for an unfiled year indefinitely. This is not theoretical — the IRS finds unfiled years, especially when there are 1099s or W-2s on file that don’t match a return.

Fraud or willful evasion. If the IRS can establish that you intentionally understated your liability — not a mistake, not an oversight, but deliberate concealment — there is no statute of limitations. They can go back as far as they can establish the conduct.

The fraud exception is harder to invoke than people think. The IRS has to actually prove intent. But it does happen, and it’s why “I didn’t know” is a better position than “I knew but didn’t bother.”

Amended Returns and What They Do to the Clock

Filing an amended return (Form 1040-X) extends the statute of limitations — but only for the items you changed.

If you amend a 2022 return in 2025 to add a deduction you missed, the IRS gets a fresh three years to examine whatever you changed. They don’t get to reopen the entire original return from scratch. But the amended items are fair game.

This is why amendments need to be filed carefully. If the only reason you’re amending is to claim a refund, you generally need to do it within three years of the original due date anyway — that’s also the window for claiming a refund. Miss that window and the refund is gone.

How Long Should You Keep Records?

If the standard window is three years and the extended window is six, the practical answer is: keep everything for at least seven years.

That means:

• All federal and state tax returns
• Business income and expense records
• Asset purchase and depreciation schedules
• Payroll records and employment tax filings
• 1099s, W-2s, and any supporting documentation

If you owned business assets — real estate, equipment, vehicles — keep records related to those assets until seven years after you dispose of them. Your basis calculation depends on original purchase price, cost of improvements, and depreciation taken. You’ll need that when the sale happens, and the IRS may want it too.

If you recently closed a business, those records don’t go away just because the entity does. The obligations follow the owner.

The Practical Takeaway

For most people with straightforward, accurate returns: the IRS has three years. After that, you’re generally in the clear.

For anyone with complex income — side businesses, rental properties, cash transactions, pass-through income from multiple entities — assume the six-year window applies and keep records accordingly. If there’s a year where something was definitely wrong, don’t wait to see if the IRS finds it. It’s almost always better to come forward through an amendment or voluntary disclosure than to hope the clock runs out.

The IRS has more tools than ever for matching income to returns — AI-driven document matching is already running on filed returns. The window they have to act is long enough that assuming you’re safe is rarely a good strategy.

This post is for general informational purposes only and does not constitute tax or legal advice. Tax rules are subject to change and individual circumstances vary. Consult a qualified tax professional before making decisions based on this content. Geiger Tax & Accounting serves clients in Amityville, NY and nationwide. Contact us at (631) 532-5622 or info@geigertax.com.