What a tax extension actually does
A tax extension gives you extra time to file your tax return, not extra time to pay taxes you owe. The IRS calls this an extension of time to file. If you request one and the IRS grants it, you get until October 15 instead of April 15 (or whatever the deadline is that year). But if you owe money, interest and penalties start running on April 15 regardless — the extension does not stop them.
The one exception: if you pay at least 90 percent of your total tax liability by the original deadline, the penalty on the remaining 10 percent is smaller. So an extension is useful if you need time to gather documents or calculate what you owe, but it is not a payment deferral. If you cannot pay by April 15, you need a different tool — an installment agreement or an offer in compromise.
Key Takeaways
- An extension to file gives you until October 15 to submit your return, but taxes owed are still due April 15 and penalties accrue if you miss that date.
- You request an extension by filing Form 4868 with the IRS before the April 15 deadline, either on paper or through tax software.
- The IRS almost always grants extensions to file; you do not have to explain why you need one or provide documentation.
- If you cannot pay taxes owed by April 15, ask about an installment agreement or short-term extension of the payment deadline instead of a filing extension.
- Paying at least 90 percent of what you owe by April 15 reduces the penalty on the remaining balance.
How to request an extension using Form 4868
You request a filing extension by submitting Form 4868 (Application for Automatic Extension of Time To File U.S. Individual Income Tax Return) to the IRS. You can file it on paper by mail, or electronically through tax software, a tax professional, or the IRS Free File program if you may have access to by income.
The form itself is short — it asks for your name, Social Security number, address, and your estimate of total tax liability and payments already made. You do not have to explain why you need the extension. The IRS grants automatic extensions to almost all filers who submit Form 4868 before the deadline. File it as early as possible; if you wait until April 14, you risk mail delays or software outages.
If you file electronically through tax software or a tax professional, the software usually handles Form 4868 automatically when you request an extension. If you mail it, send it to the address listed on the form for your state. Keep a copy for your records.
What happens after you submit Form 4868
Once the IRS receives your Form 4868 before the deadline, your extension is granted. You do not receive a confirmation letter in most cases — the absence of a rejection is your confirmation. You now have until October 15 to file your actual return.
The extension applies only to filing, not to payment. If you owe taxes, they are due April 15. If you do not pay by then, the IRS charges a failure-to-pay penalty (currently 0.5 percent per month of unpaid tax) and interest (currently around 8 percent annually, adjusted quarterly). These accrue even if you file your return on time in October.
If you pay some of what you owe by April 15, the penalty applies only to the unpaid portion. Paying 90 percent or more by the deadline reduces the penalty on the remainder from 0.5 percent per month to 0.25 percent per month.
When to use an extension versus a payment plan
A filing extension is the right tool if you need time to gather documents, wait for a K-1 or other form from a business partner, or calculate a complex return. It is not the right tool if you know you owe money and cannot pay it by April 15.
If you cannot pay by April 15, the IRS offers installment agreements that let you pay in monthly chunks. A short-term extension (120 days) is also available if you need just a few months. Both of these are separate from a filing extension and require a different request. You can request both at the same time — an extension to file and a payment plan — but they are distinct.
Do not assume an extension to file will buy you time on payment. It will not. If you need payment time, contact the IRS directly or work with a tax professional to set up an installment agreement before April 15.
Penalties and interest if you miss the April 15 payment deadline
If you file an extension but do not pay taxes owed by April 15, the IRS charges two separate penalties. The failure-to-pay penalty is 0.5 percent of unpaid tax per month (or part of a month), up to 25 percent total. The interest is calculated daily and compounds, currently around 8 percent per year but adjusted quarterly.
Example: if you owe $5,000 and pay nothing by April 15, by October 15 you will owe roughly $5,200 to $5,300 in interest and penalties alone, depending on the exact interest rate that quarter. The longer you wait, the more you owe.
If you pay at least 90 percent by April 15, the failure-to-pay penalty on the remaining 10 percent drops to 0.25 percent per month instead of 0.5 percent. This is a small but real savings if you are going to miss the deadline anyway.
What to do if you cannot file Form 4868 by April 15
If you miss the April 15 deadline without filing Form 4868, you can still file it late, but the IRS will charge a failure-to-file penalty in addition to failure-to-pay penalties. The failure-to-file penalty is 5 percent of unpaid tax per month, much steeper than the 0.5 percent failure-to-pay penalty.
File Form 4868 as soon as you realize you will miss the deadline. The sooner you file it, the sooner the extension clock starts and the sooner you can file your return. If you are very late and owe a large amount, contact the IRS or a tax professional about penalty relief; the IRS sometimes abates penalties for first-time filers or those with reasonable cause.
How to pay taxes owed if you cannot pay in full by April 15
If you have filed an extension but cannot pay by April 15, you have three main options. The first is to request a short-term extension of the payment deadline — the IRS will give you up to 120 days extra to pay without setting up a formal installment agreement. You request this by calling the IRS at 1-800-829-1040 or through your online IRS account.
The second is to set up an installment agreement, which lets you pay in monthly installments. You can request this online through the IRS website, by phone, or by mail. The IRS charges a setup fee (currently $31 to $225 depending on the method) and charges interest on the unpaid balance each month.
The third is to request an offer in compromise if you genuinely cannot pay what you owe. This is a settlement where you pay less than the full amount owed. It is harder to get approved for and takes longer, but it is an option if your financial situation is dire.
Frequently Asked Questions
Does filing an extension delay when I have to pay taxes?
No. An extension to file delays when you submit your return, not when you pay. Taxes owed are due April 15 regardless of whether you file an extension. If you cannot pay by April 15, you need a payment plan or short-term payment extension, not a filing extension.
Can I file Form 4868 after April 15?
Yes, but you will owe a failure-to-file penalty on top of any failure-to-pay penalty. File it as soon as you realize you need it. The penalty is 5 percent of unpaid tax per month, so filing late is expensive.
What if I file an extension but do not file my return by October 15?
The failure-to-file penalty continues to accrue. You will owe 5 percent per month for every month you do not file, up to 25 percent total. File your return as soon as you can, even if you cannot pay what you owe.
Do I have to explain why I need an extension?
No. Form 4868 does not ask for a reason, and the IRS does not require one. The extension is automatic if you file the form before the deadline. You do not need to justify it.
Can I request an extension if I am self-employed or have a business?
Yes, Form 4868 works for self-employed people and business owners. However, if you have a business, you may also need to file a separate extension for your business return (Form 1065, 1120, or 1120-S depending on your structure). Check with a tax professional about what forms you need.