You can get a 6-month extension on your tax return, but that doesn't mean you're off the hook on tax day

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A tax extension doesn't mean you have more time to pay your tax bill.

• The deadline to file your 2018 federal tax return is April 15 in most states.
• You can file for a six-month extension if you have a complicated tax situation and need more time.
• A tax-filing extension pushes the deadline to October 15, but you still need to pay what you owe by April 15 or accrue interest and/or a penalty.

Taxes are due April 15 - or April 17, if you live in Maine or Massachusetts - this year. 

If you can't get everything together for the deadline, you can file for a tax extension with the IRS, which pushes the due date back six months, to October 15. 

President Donald Trump filed an extension to submit his 2017 tax return, as is common among high earners and taxpayers with complicated financial situations. Mitt Romney filed for an extension in 2012 for his 2011 tax return while running for president as a Republican.

But filing a tax extension doesn't mean you're off the hook for any unpaid federal income taxes you owe.

If you expect to have a tax bill, you're responsible for estimating the amount and paying it in full on April 15 or April 17. A tax bill is the result of underpaying taxes throughout the year; either your employer didn't withhold enough money from your paycheck to cover your taxes, or if you're self-employed, you didn't pay enough estimated quarterly taxes.

If you don't pay your tax bill in full by tax day - whether you file an extension or not - you'll pay a penalty, typically 0.5% to 1% of any unpaid tax owed at the deadline, charged each month the tax remains unpaid (the total possible penalty is 25% of the amount owed). On top of that, the tax bill is also subject to federal interest rates.

However, the penalty is waived for taxpayers who file an extension and paid at least 85% of their tax liability throughout 2018, the IRS says - usually it's 90%, but the threshold was lowered to account for changes in the tax-filing process under tax reform.

How to file a tax extension

Taxpayers who don't file a tax return or a tax extension by the April deadline will be charged a penalty of 5% of the outstanding tax bill for every month the return is late. 

There are a few easy ways to file an extension:

• File online for free (if your adjusted gross income is under $66,000) with the IRS' e-file partners, including H&R Block and TaxAct - find the full list here. 
• Use IRS Form 4868 to send in your extension request by mail.
• Make a payment on the IRS website that covers all or part of your estimated tax bill - it will automatically process an extension for your tax return.

• Read more of our 2019 Tax Day coverage:
• Your state tax refund may take longer to hit your bank account than your federal refund - here's how to find out when it's coming
• It took me under an hour to file my taxes this year thanks to a time-saving strategy that's available to anyone
• I'm filing my taxes with TurboTax and will probably get one of my smallest refunds ever, and I'm happy about it
• After someone stole my tax refund 2 years ago, I found the best way to protect myself is also the easiest

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