If you missed April 15, your late federal taxes are due right now. For the 2025 tax year, the filing and payment deadline was April 15, 2026, and any balance unpaid after that date starts accruing penalties and interest the next day.1Internal Revenue Service. Individual Tax Filing There’s no separate later “due date” for late taxes: the debt is immediate, and the longer it sits, the more it costs.
A few dates still matter after April 15, though, and knowing which ones apply to you decides how much this ends up costing.
What the October 15 Extension Actually Does
Filing Form 4868 by April 15 buys you six more months to submit the return, moving the filing deadline to October 15, 2026.2Internal Revenue Service. Form 4868 – Application for Automatic Extension of Time To File U.S. Individual Income Tax Return That’s the single most misunderstood date in the tax calendar. The extension applies to the paperwork only. Any tax you owe was still due April 15, and interest and the failure-to-pay penalty start running the day after.3Internal Revenue Service. When to File
If you file by October 15, the extension shields you from the failure-to-file penalty. Miss October 15 and that protection disappears; the IRS calculates penalties as if you never requested extra time. So even if you cannot pay, file the return or at least submit Form 4868. Filing is free. Not filing is where the biggest penalties stack up.
What Each Month of Lateness Costs
The IRS treats late filing and late payment as two separate offenses, each with its own rate.
Failure-to-File Penalty
The failure-to-file penalty is 5% of the unpaid tax for each month or partial month the return is late, up to a 25% cap. For returns due after December 31, 2025, there’s also a minimum: if you file more than 60 days late, the penalty is at least $525 or 100% of the unpaid tax, whichever is smaller.4Internal Revenue Service. Failure to File Penalty That minimum catches people who assume a small balance means a small penalty.
Failure-to-Pay Penalty
The failure-to-pay penalty is 0.5% of the unpaid tax per month, capped at 25%. If you filed on time and are on an approved installment agreement, the rate drops to 0.25% per month. If you ignore an IRS notice of intent to levy, it jumps to 1% per month.5Internal Revenue Service. Failure to Pay Penalty
How They Combine
When both penalties apply in the same month, the failure-to-file penalty is reduced by the failure-to-pay amount, so the combined monthly hit is 5% (4.5% plus 0.5%) rather than 5.5%.6Office of the Law Revision Counsel. 26 USC 6651 – Failure To File Tax Return or To Pay Tax After five months, the failure-to-file portion maxes out at 25%. The failure-to-pay penalty keeps running until your balance hits zero or it also reaches 25%.
Interest
On top of both penalties, interest accrues on the unpaid balance (including on the penalties themselves). For the first quarter of 2026, the individual underpayment rate is 7% per year, compounded daily.7Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026 The IRS resets this rate quarterly. Interest cannot be waived, even if the underlying penalties are removed.
If the IRS Owes You Money, You Also Have a Deadline
Being “late” cuts both ways. If a refund is coming to you, you generally have three years from the date the return was filed, or two years from the date the tax was paid, whichever is later. Returns filed before the due date count as filed on the due date for this clock, and withholding and estimated payments count as paid on that same date.8Internal Revenue Service. Time You Can Claim a Credit or Refund
Once that window closes, the refund is forfeited to the U.S. Treasury. The IRS won’t warn you it’s about to expire. People who never file because they “don’t owe anything” can lose thousands in refundable credits they were entitled to. If you claim a refund more than two years after paying the tax, the refund is also capped at what you actually paid in the two years before you filed the claim, which can shrink the amount even when you’re still inside the three-year window.
Getting on a Payment Plan
If you cannot pay the balance in full, an installment agreement converts the debt into a monthly obligation. You pick a payment date between the 1st and 28th of the month, and that becomes your recurring deadline for the life of the plan.9Internal Revenue Service. Instructions for Form 9465 A single missed payment can default the agreement, at which point the IRS may demand the full remaining balance and move to bank levies or wage garnishments.
Setup fees depend on how you apply and how you pay:10Internal Revenue Service. Payment Plans; Installment Agreements
- Direct debit set up online: $22
- Direct debit set up by phone, mail, or in person: $107
- Other payment methods online: $69
- Other payment methods by phone, mail, or in person: $178
Short-term plans of 180 days or less have no setup fee. Reinstating a defaulted plan through the online payment agreement tool costs $10.11Internal Revenue Service. Online Payment Agreement Application Taxpayers with adjusted gross income at or below 250% of the federal poverty level pay no setup fee for a direct debit plan; if direct debit isn’t possible, the fee drops to $43 and may be reimbursed once the plan is completed. The IRS usually flags eligibility automatically from your income data.10Internal Revenue Service. Payment Plans; Installment Agreements
Interest keeps running on the balance while you’re on a plan. The one built-in break: the failure-to-pay penalty rate is cut from 0.5% to 0.25% per month once the agreement is in place.5Internal Revenue Service. Failure to Pay Penalty
Getting Penalties Removed
Even after penalties are on your account, you have two main routes to have them reduced or wiped out. Neither touches interest.
First-Time Abatement
If you filed all required returns for the prior three tax years and had no penalties in that window (or had any prior penalties removed for an acceptable reason), you can request first-time penalty abatement. The IRS treats it as an administrative waiver and generally grants it without asking you to explain what happened.12Internal Revenue Service. Administrative Penalty Relief It covers failure-to-file, failure-to-pay, and failure-to-deposit penalties, and it’s one of the most underused tools available to someone who had a single bad year.
Reasonable Cause
If you don’t qualify for first-time abatement, you can ask for relief based on reasonable cause. The IRS decides case by case whether you exercised ordinary care but still couldn’t meet the deadline. Circumstances that typically qualify include serious illness or a death in the immediate family, fires or natural disasters, and inability to obtain necessary records.13Internal Revenue Service. Penalty Relief for Reasonable Cause
What generally doesn’t qualify: not knowing about the deadline, relying on a tax professional who dropped the ball, or simple mistakes. The IRS is explicit that lack of funds alone isn’t reasonable cause, though it can be considered alongside other factors.13Internal Revenue Service. Penalty Relief for Reasonable Cause
The Ten-Year Outer Limit
Every tax debt eventually expires. Under 26 U.S.C. § 6502, the IRS has ten years from the date of assessment to collect.14Office of the Law Revision Counsel. 26 USC 6502 – Collection After Assessment The assessment date is usually the day you filed the return, or the day the IRS recorded the debt through an audit or a Substitute for Return prepared on your behalf. Once the Collection Statute Expiration Date passes, the debt is legally uncollectible and any existing liens must be released.
Several actions pause that clock:15Taxpayer Advocate Service. Collection Statute Expiration Date CSED
- An offer in compromise suspends the clock while the IRS reviews it, plus 30 days if rejected, plus any appeal time.16Internal Revenue Service. Time IRS Can Collect Tax
- Bankruptcy suspends the clock for the length of the case plus six months afterward.
- Requesting an installment agreement suspends the clock while the request is pending, plus 30 days if rejected.
- A Collection Due Process hearing suspends the clock until the determination is final, including any court appeals.
- An innocent spouse claim suspends the clock for the requesting spouse until resolved, plus 60 days.
Each of these can push the ten-year mark further out than you’d calculate from the assessment date alone. If you’re hoping to run out the clock, be aware that ordinary interactions with the IRS often add to the timeline rather than shorten it.
Automatic Extensions You May Already Qualify For
Two situations move all tax deadlines back without your having to request anything.
When FEMA declares a disaster, the IRS postpones filing and payment deadlines for affected taxpayers. You don’t have to live in the disaster zone: if your records or your tax preparer are located there, or you rely on a Schedule K-1 from a partnership or S corporation in the area, you can call the IRS Disaster Hotline at 866-562-5227 with the FEMA disaster number to request relief.17Internal Revenue Service. FAQs for Disaster Victims
Military personnel serving in a designated combat zone get an extension equal to the time spent in the zone plus 180 days after leaving. The extension covers filing, paying, and other tax-related actions, and no penalties or interest accrue during it.18Internal Revenue Service. Extension of Deadlines – Combat Zone Service
If neither applies, the answer to when your late taxes are due is today, and the cheapest day to pay them is the earliest one you can manage.