CPAs bring a late-filing client current by filing the last six unfiled years, checking for any IRS-prepared substitute for return, and sequencing the filings by refund and risk exposure rather than by year. Penalties and interest get estimated up front so the client can plan for the bill before returns go in, and first-time penalty abatement is the first relief option to check once returns are filed.

How many years does a CPA need to file

The standard is six years of returns. IRS Policy Statement 5-133 sets the normal enforcement period for delinquent filers at six years, so a preparer intakes a client's last six years of income documents (W-2s, 1099s, K-1s) as the default scope. A client who has not filed in ten years still generally only needs the most recent six brought current, though the IRS can require more years for illegal-source income, an active exam, or an open collection case. Filing beyond six years is voluntary, sometimes worth doing to claim a refund year or close a state matter, but it is not the compliance floor.

What order should the returns be filed in

Filing order is not automatically oldest-first. A CPA sequences returns by which years still carry a refund, which years are closest to a statute of limitations, and which years the IRS has already flagged with a notice or substitute for return. A refund is only claimable if the return is filed within three years of its original due date, so a refund sitting in year one of a six-year gap needs to go in before that clock runs out, even if the years in between get filed later. A year with an existing CP59 notice or open case moves to the front of the queue because it is actively accruing enforcement risk. Balance-due years with no urgency get filed last, once records are reconstructed and penalty exposure is estimated.

What happens if the IRS files first

If a return goes unfiled long enough, the IRS can prepare one for the taxpayer under IRC Section 6020(b). A substitute for return uses only the income the IRS has on file from W-2s and 1099s, with no dependents, no filing status optimization, and no deductions beyond the standard amount, so it almost always overstates the tax owed. Under IRC 6020(b), a return the IRS prepares this way "shall be prima facie good and sufficient for all legal purposes," meaning it stands as valid until the taxpayer files an accurate return to replace it. Filing the real return corrects the liability and is standard practice once a client is caught up on records.

How much do the penalties and interest cost

Two separate penalties apply to a late return with a balance due, and both accrue by the month. The failure-to-file penalty is 5% of the unpaid tax for each month or partial month the return is late, capped at 25% of the tax due. The failure-to-pay penalty is 0.5% of the unpaid tax per month, also capped at 25%, and it keeps running even after the failure-to-file penalty maxes out at month five. When both apply in the same month, the IRS reduces the failure-to-file penalty by the failure-to-pay amount, so the combined rate is 5% per month, not 5.5%. Interest accrues separately under IRC Section 6601 from the original due date until the balance is paid, and it does not stop when a return is filed or when the failure-to-file penalty hits its cap. A client who owes $20,000 and is two years late can be looking at $5,000 in failure-to-file penalty, a smaller failure-to-pay amount on top, and two years of compounding interest on the whole balance.

What if the client is missing records

Reasonable reconstruction is acceptable when original records do not exist. A CPA can pull IRS wage and income transcripts to rebuild reported income, and reconstruct expenses from bank statements, prior-year returns, and vendor records the client can still produce. The IRS does not require photocopies of every original document before a return can be filed; a documented, good-faith reconstruction supports the numbers on the return and is standard practice for multi-year catch-up work.

Can the penalties be reduced

First-time penalty abatement (FTA) removes the failure-to-file and failure-to-pay penalties for a client with a clean recent record, and it is the first relief option to raise once returns are filed. To qualify, the client must have timely filed the same return type for the prior three years with no penalties assessed in that window other than an estimated tax penalty. FTA is requested by phone, written statement, or Form 843, and covers failure-to-file, failure-to-pay, and failure-to-deposit penalties. A client catching up six years of returns typically has only one year eligible, since the clean-history test looks at the years right before the one being abated. Target FTA at the highest-penalty year in the batch rather than assume it clears the whole filing.

FAQs

How many years of returns does a CPA typically file for a non-filer client? The default is the last six years, based on the IRS's standard six-year enforcement period under Policy Statement 5-133. The IRS can look back further in cases involving illegal-source income or an active exam, but six years is the routine scope for intake.

Should the oldest unfiled year always be filed first? No. Filing order depends on which years hold refunds nearing the three-year claim deadline, which years already have an IRS notice or substitute for return, and which years are lower risk. A refund year with a closing statute gets priority over an older year that only has a balance due.

Do penalties stop accruing once the return is filed? The failure-to-file penalty stops once the return is filed, but it may already be capped at 25% if the return was five or more months late. The failure-to-pay penalty and interest under IRC 6601 continue accruing on any unpaid balance until it is paid in full, regardless of when the return was filed.

What if the client cannot produce complete records? Reasonable reconstruction from IRS wage-and-income transcripts, bank statements, and available third-party records is acceptable. The IRS does not require original source documents for every line item before a return can be filed.

Is first-time abatement worth requesting for a multi-year catch-up? Yes, but it typically applies to only one year, since it requires three years of clean filing history immediately before the year requesting relief. A CPA should apply FTA to the year with the largest penalty exposure rather than expect it to cover the entire multi-year filing.

Late-filer engagements run smoother when the intake step captures every unfiled year, pulls transcripts before assuming records are gone, and prices the penalty and interest exposure before the client signs off on the filing order.