Submitting your tax return on time is one of the most fundamentally important obligations you have as a taxpayer. In most years -- including 2019 -- that means your Form 1040 and accompanying forms and schedules must be sent to the IRS by April 15. If April 15 falls on a weekend or a holiday, your tax return has to be submitted by the next business day. 

But what happens if you don't submit your return by that date, or don't submit it at all? The answer depends whether you owe money or not -- and if you do owe, the penalties for being late with your return can be quite substantial. 

1040 form and tax refund check.

Image source: Getty Images.

What's the penalty for a late tax return if you don't owe money?

If it turns out that you don't owe the IRS anything, and you're tardy with your tax return, you won't be penalized.

You'll still want to submit your tax forms ASAP so you can claim your refund. If you hope to get money back from the IRS for the 2018 tax year, the absolute last date you can submit a return is April 15, 2022 -- or Oct. 15, 2022, if you submitted a request for an extension to file, and made that request before April 15, 2019. 

If you miss this deadline, any unclaimed refund owed to you will become the property of the U.S. Treasury and is lost to you forever.

What's the penalty for a late tax return if you do owe money?

If you're going to need to send some cash to the IRS, it's much more important that you're on time with your return. You'll have to submit your forms by April 15, or file IRS Form 4868 by this date. Form 4868 is called the Application for Automatic Extension of Time to File U.S. Individual Income Tax Return, and it does just what it sounds like: It gets you an automatic extension on the deadline for your tax forms. 

If you file Form 4868, you'll have until Oct. 15 (or the next business day if the 15th falls on a holiday or weekend) to submit your tax return. But be aware that this extension applies to your time to file. You still have to pay your taxes on time to avoid a late-payment penalty. This penalty can be avoided if you've paid at least 90% of what you owe, you've requested an extension to file, and you pay the remaining 10% by the October deadline.

If you don't file an extension and miss the April 15 deadline, or if you file an extension and you miss the October deadline, that's when the real trouble starts. The IRS begins imposing penalties as soon as you're one day late with your tax return, and the penalties for late filing are much higher than the penalties for paying late. 

The penalty for filing late equals 5% of the amount of tax you owe for each month or part of a month your return is tardy. The maximum you could end up owing in late filing penalties is 25% of the unpaid tax amount. However, if you file more than 60 days after the tax deadline, the minimum penalty is the lesser of $205 or 100% of the unpaid taxes owed to the IRS. 

The penalty for paying late -- if you file on time -- is just 0.5% of the taxes you still owe for each month or part of a month you're late, up to a maximum of 25% of the outstanding balance due. This penalty is waived, though, if you owe the late filing penalty. 

As you can see, it's going to cost you a lot more not to file than it would if you filed on time and just didn't pay on time. 

What if you're having a hard time submitting your tax return?

If you're having difficulty completing your tax return by the deadline, consider getting help.

If you make $55,000 or less, have difficulty with English, or are disabled or elderly, you can get free assistance from volunteer tax preparers (the IRS has details).  You can also use free e-filing if you make $66,000 or less. Many of the e-file programs aim to make submitting your returns easy by asking simple questions to help you complete your forms. 

If you can't qualify for free assistance or need more advanced help, it may be worth paying a certified public accountant or other qualified tax preparer. It's not usually very expensive to get an accountant to help with a simple tax return and can sometimes cost you less than paying penalties for submitting your return late.

Do your best to get your returns submitted on time

As you can see, filing your tax return late could cost you a whole bunch of money if you owe taxes. But you still have plenty of time to get your forms taken care of, or to request an extension until the October deadline if you need extra time. Just don't wait to act, because April 15 will be here before you know it.