If you filed an extension in April, the clock is nearly out. For 2025 returns, the extended deadline for individual returns on Form 1040 — including Schedule C for sole proprietors and single-member LLCs — and for calendar-year C corporations on Form 1120 is Thursday, October 15, 2026. There is no second extension for those returns.
Most late returns are not late because of the tax return itself. They are late because the books behind it were never finished. Here is what the extension did, and what needs to be done in the next two weeks.
What the extension did and did not do
An extension gave you more time to file, not more time to pay. Any tax owed for 2025 was due on April 15. If you underpaid, the IRS has been charging interest on the balance since then, and a failure-to-pay penalty generally accrues at 0.5% of the unpaid tax per month. Both keep running until the balance is paid, so finishing sooner costs less.
Missing October 15 is more expensive. The failure-to-file penalty is generally 5% of the unpaid tax for each month or partial month the return is late, up to 25%. Filing on time, even with a balance you cannot pay in full yet, avoids that penalty and opens the door to an IRS payment plan.
One check worth making: the IRS sometimes postpones deadlines for taxpayers in federally declared disaster areas. If your area was affected this year, confirm your actual due date with your preparer before assuming October 15.
What your preparer needs from your books
Your preparer needs a full-year 2025 profit and loss statement and a December 31, 2025 balance sheet — and both need to be built on reconciled accounts. That means every business bank account, credit card, and loan reconciled through December against the actual statements, not just categorized from the bank feed.
Beyond the two reports, have ready: payments made to contractors and copies of the 1099s you issued, any 1099-K or 1099-NEC forms you received, loan statements showing year-end balances and interest paid, a list of equipment or vehicles bought or sold during the year, mileage records if you deduct vehicle use, and the estimated tax payments you made for 2025 with dates and amounts.
If you own part of a partnership or S corporation, its extended deadline was September 15, so your Schedule K-1 should have arrived. A missing K-1 is a common reason individual returns stall at this point — chase it now.
If you are self-employed and want to make a SEP-IRA contribution for 2025, it can generally be made up to the extended due date when an extension was filed. The contribution limit depends on your net self-employment earnings, which is one more reason the P&L has to be right.
If the books are not done, finish the year in order
Work month by month from the last period you know is correct. Reconcile each account for each month before moving on, so an error is caught where it happened instead of buried in an annual total. Separate out personal transactions, make sure owner draws are not sitting in expenses, and make sure credit card payments are not counted as expenses a second time.
Do not hand your preparer a box of statements two days before the deadline. Preparing a return from raw statements costs more, leaves less time for questions, and makes errors more likely. The goal is to deliver finished statements with days to spare.
Get 2025 finished this week
If your 2025 books are behind, Evolv Bookkeeping's cleanup is $199 for each month behind, and the catch-up is completed within 2 days, guaranteed in writing. You get reconciled statements your preparer can work from while there is still time before October 15.
After that, ongoing bookkeeping is $199 per month flat, with 1099 prep at year end, so next year's return starts from books that are already done. No contracts, cancel anytime. Get an instant quote on our homepage.