A year of unentered books is one fixed fee to fix and an open-ended bill to ignore. This worksheet puts the two side by side: a written catch-up quote on the left, and on the right the IRS penalties that keep accruing while the return you cannot file stays unfiled. It prints the penalty rules from irs.gov, including the one that charges S corporations and partnerships $255 per owner per month with no tax due at all.
A year of catch-up bookkeeping is a one-time, fixed fee that stops growing the day the quote is written. The cost of not doing it is not fixed: it compounds monthly through three IRS penalties that keep accruing while the return you cannot file sits unfiled, and it shows up again the moment a lender or buyer asks for statements you do not have. For most businesses a year behind, the penalty column overtakes the catch-up column within a few months, and for an S corporation or partnership it does so even when no tax is owed. Below are the rules, the arithmetic, and a two-column worksheet to run on your own numbers.
Books that are a year behind usually mean a return that is late, because a return cannot be prepared from bank statements alone. The IRS charges for that lateness under three separate rules, all from irs.gov as published this year.
Failure to file (Forms 1040 and 1120). Five percent of the unpaid tax for each month or part of a month the return is late, capped at 25%. If the return is more than 60 days late, a floor applies: for returns due after 31 December 2025 the minimum is $525 or 100% of the tax owed, whichever is smaller. When the failure-to-pay penalty applies in the same month, the failure-to-file rate is reduced by that 0.5%, so the combined charge is still 5% a month, and the failure-to-file part maxes out after five months.
Failure to pay. Half a percent of the unpaid tax per month or part of a month, up to 25%, and it keeps running after the failure-to-file penalty has capped. It rises to 1% a month ten days after a notice of intent to levy, and drops to 0.25% for individuals on an approved payment plan who filed on time. Interest is charged on top of both penalties and, by law, cannot be removed unless the penalty is.
Late pass-through returns (Forms 1065 and 1120-S). This is the one most owners have never priced. For returns due after 31 December 2025 the penalty is $255 per month, per partner or shareholder, for up to 12 months, and it is charged whether or not any tax is due. Under §6698 and §6699 the penalty attaches to the entity return itself, so “we did not owe anything” is not a defence. It is multiplied by every person who was a partner or shareholder at any point in the year.
Three worked examples, each using only the rates above. Substitute your own figures; the shape of the result is what matters.
| Situation | Rule applied | Penalty before interest |
|---|---|---|
| Sole proprietor, Form 1040 with $12,000 of tax due, filed and paid 5 months late | 4.5% × 5 months failure to file + 0.5% × 5 months failure to pay = 25% of $12,000 | $3,000 |
| S corporation with three shareholders, Form 1120-S filed 8 months late, no tax due | $255 × 3 shareholders × 8 months | $6,120 |
| Single-member LLC with $400 of tax due, Form 1040 filed 4 months late | Over 60 days late, so the floor applies: lesser of $525 or 100% of tax | $400 (the entire tax bill, again) |
Two things the table shows that the general advice misses. First, the S corporation with nothing to pay owes more than the sole proprietor with a five-figure tax bill, because the pass-through penalty is a per-head, per-month count rather than a percentage. Second, the floor turns a small balance into a doubled bill: the $400 filer pays the tax and then pays it again as penalty. Neither number depends on how messy the books are. They depend only on the calendar.
Fill in the left column from a written catch-up quote and the right column from the rules above. Use the date you realistically expect to file, not the date you hope to.
| Line | Column A — catch up now | Column B — keep waiting |
|---|---|---|
| Catch-up fee for the year (fixed, written) | $ ______ | $ 0 today, same fee later |
| Months the return will be late by the time you file | ______ | ______ (usually more) |
| Failure to file: 5% × months (max 25%) × unpaid tax, or the $525 floor | $ ______ | $ ______ |
| Failure to pay: 0.5% × months × unpaid tax | $ ______ | $ ______ |
| Pass-through: $255 × partners or shareholders × months (max 12) | $ ______ | $ ______ |
| Interest on tax and penalties (IRS rate, compounding daily) | $ ______ | $ ______ |
| Lender, buyer or grant deadline missed for lack of financials (what a lender actually asks for is in the investor-ready books checklist) | $ 0 | $ ______ (your estimate) |
| Total | $ ______ | $ ______ |
The catch-up fee appears in both columns, because it is not avoided by waiting; it is only deferred. That is the whole point of the worksheet. The only line that is zero in column A and positive in column B is the one most owners are actually worrying about when they call.
Penalties are assessed per return, per year. Two years behind is two stacks of penalties running in parallel, each with its own 25% cap and its own twelve-month pass-through clock, and the older year has usually already hit its maximum. That is why the practical advice is to close the oldest open year first: it is the one where the failure-to-file component has stopped growing and the reasonable-cause argument is weakest. Our month-end close checklist is what keeps a caught-up year from becoming a behind one again.
Extensions do not change the arithmetic as much as people hope. Form 4868 or Form 7004 extends the time to file, not the time to pay, so the failure-to-pay penalty and interest start on the original due date regardless. And an extension has to be requested by the original due date; it cannot be applied after the fact to a year that is already behind.
What drives the quote: number of accounts, transaction volume, whether payroll and inventory are involved, and how much of the year is clean-up rather than catch-up. What does not drive it: how embarrassed you are about the shoebox. A never-kept year built from statements is routine work.
The IRS can remove failure-to-file and failure-to-pay penalties for reasonable cause, and its first-time abatement program can remove a first penalty for a filer whose prior three years were clean. Relief is requested, not automatic, and it is far easier to argue once the return is actually filed. Small partnerships of ten or fewer individual partners may also qualify for presumed relief under Rev. Proc. 84-35 if every partner reported their share on a timely personal return. None of this reduces interest unless the penalty itself is removed, and none of it applies to a year you still have not filed.
Only if you can finish before the penalties overtake the fee. A year of catch-up done in evenings typically takes months; the S corporation example above accrues $765 a month for three shareholders while it waits. Get the written quote first and compare it with the monthly penalty figure for your entity type.
Yes. The Form 1120-S penalty is $255 per shareholder per month for up to 12 months and is charged regardless of tax due. The same rule applies to partnerships filing Form 1065.
It stops the failure-to-file penalty if filed by the original due date and the return is then filed by the extended date. It does not stop the failure-to-pay penalty or interest, which run from the original due date on any unpaid tax.
Numerawise quotes it as a fixed written price after a free review of your statements, scoped on accounts, volume and how much is clean-up rather than catch-up. There is no hourly meter and the price does not change once the statements are in hand.
When the worksheet says the right-hand column is winning, the catch-up bookkeeping page explains what to send, how the month-by-month rebuild works and how to get the fixed quote.
Tell us what you’re working on. We respond same business day.
Founder of Numerawise Solutions, established MMXXIV in Atlanta. Intuit ProAdvisor Gold tier. Former Intuit Technical Support engineer. Has personally led two hundred accounting software conversions for US small businesses since founding the practice. Reachable directly at [email protected].