Sometimes after you file a tax return, you realize it was wrong. Sure, we pride ourselves on putting together valid and accurate returns, but that does not mean that you can’t come across income or deductions that you forgot to include, or didn’t know you could include, the first time. So this week I wanted to go over what one should do if you realize you need to amend a tax return.

The first point here is just bluntly to state that, yes, you can file an amended tax return. In general, the IRS gives you three years to do so. That means that there rarely is a time crunch going on with these returns, but you should still get it done as quickly as possible. After all, if the changes mean you get more money back, why wouldn’t you want to receive it faster? And if you will owe money due to the changes, the sooner you pay, the less penalties and interest that will accrue.

There are some things, however, that will not require filing an amended return. For instance, any math errors will be corrected by the IRS and handled appropriately. Also, if there are any forms or schedules you neglected to include, the IRS will mail out a request for them if needed.

This means that what usually requires amending are when things were not reported on the original return. Was there some income you forgot about or didn’t realize was taxable that you should have included? Were there deductions that you did not realize you qualified for that you wished you claimed? Those are the types of things that will be at play here.

Unfortunately, the amended return is not really as easy to file as the original return, because it cannot be processed electronically. Instead, this has to happen on a special form, 1040X, which must be mailed in. The form also includes a space on it to explain the changes you are making to the original return. And as a little note, if this is something that is affecting returns from multiple years (which is allowed under that three-year window) you need a separate form, in a different envelope, for each year.

A final couple quick notes, if you have not received a refund for your 2017 taxes, wait until you do receive it before sending in an amended return. You can cash that original check refund, though, while waiting for the amendments to go through. And if you then want to check the status of the amended return, the IRS offers a “Where’s My Amended Return” page, where you can track it.

This is similar to the agency’s “Where’s My Refund” page, which you will want to use if by some chance you are someone who has not yet received an expected 2017 refund.  Almost everyone has received their refunds by this point (assuming the tax return was filed on time), but there are some things that could hold it up, especially for those returns filed in the final hours. That page will give you the best information as to where things stand.