Don't freak out, consider whether or not you need to file an amended return.
Should I file an amended tax return?
You've meticulously filled out and submitted your taxes. But there was still a mistake (or two) OH NO!
Don't freak out.
First-- what sort of mistake was it?
If it was...
A. a math error
B. you forgot to attach a form or schedule
Then you don't need to file an amended return. The IRS can fix simple math errors. And if they need a form from you, they will send a letter asking for it.
If it was...
If there was a change of:
Filing status
Income
Deductions
Credits
Tax liability
Then yes, you should file an amended return.