Filing an income tax return after the annual April deadline usually isn’t the end of the world, but there’s a right way and a wrong way to do it. Here are some common mistakes to avoid if you’re filing taxes late.

1. Doing nothing in April

• If you plan to file your tax return late, the IRS is usually fine with that. Just request a tax extension by filing Form 4868 to get more time. The catch, however, is that you need to request that extension by the tax filing deadline.

• Forget to do that and you’ve opened yourself up to a late-filing penalty of 5% of the amount due for every month or partial month your return is late. The maximum penalty is 25% of the amount due. So if you owe, say, $1,000 in taxes, that could mean shelling out an extra $250.

2. Assuming tax is all you’ll owe

Paying later means paying more, because you’ll owe interest on any amount outstanding after the April deadline, even if you get an extension.

• The IRS may also assess a late-payment penalty, which normally is 0.5% per month of the outstanding tax not paid by the April deadline (the maximum penalty is 25%). In 2019, you might be able to catch a break if you’ve paid at least 85% of your actual tax liability by the April deadline and you pay the rest when you send in your return.

• The bottom line is that if you owe taxes, it may be a good idea to pay as much as you can in April, when you request the extension.

» MORE: Estimate your tax burden with our free tax calculator

3. Assuming you have to ask for an extension

In a few circumstances, the IRS will give you an extension even if you don’t ask for one. Not knowing the rules could cost you time and confuse matters.

• If you’re a U.S. citizen or resident who lived and worked outside of the country on the April deadline, for example, you get more time to file and pay without having to request an extension.

• People affected by certain natural disasters automatically get more time to file and pay, as well; check the IRS’s list of qualifying disasters. Some members of the military also get more time automatically, depending on where they are and what they’re doing (learn more here).

4. Assuming you have 6 extra months to get it together

The standard extension can buy you an extra six months to file, which gets you to the middle of October. But if you’re one of the few who get an automatic extension, don’t assume you have the same amount of time.

• That out-of-the-country crowd mentioned earlier gets just two extra months to file, for instance; the amount of extra time varies for people affected by certain natural disasters.

• Members of the military could get more than six months in some situations.

5. Forgetting about your extension deadline

• Miss your extension deadline and the IRS can sock you with that 5% penalty for filing your taxes late.

• If you really blow the deadline and your return is over 60 days late, you’ll pay either $210 (adjusted for inflation) or what you still owe, whichever figure is smaller. And remember, that’s on top of what you still owe in taxes.

• The good news is that the IRS may throw you a lifeline: You might not have to pay the penalty if you have “a reasonable explanation” for filing late and attach a written explanation to your return.

6. Assuming the IRS will hate you

There’s no need to risk making big mistakes on your tax return or missing valuable deductions because you’re rushing to meet the filing deadline and think the IRS will blacklist you for seeking an extension. Filing late is common. In fact, extensions are a fact of life for many investors who don’t get their K-1s, which are statements of income from partnerships, until after April.

There’s no scarlet letter for filing late — as long as you get an extension. If anything, deciding to keep your tax return on your to-do list beyond April may warrant a badge of courage.