In 2020 I filed my return early. After I filed, something changed and my refund doubled. Why did this happen? I changed no information.

[Mooby]

I called tech support and they said a tax law had changed resulting in a bigger refund and the IRS would figure it out and send the bigger refund I only got my original refund.

[VolvoGirl]

Did you have any unemployment?  If you filed early before the exclusion, the IRS will recalculate your return for the new 10,200 unemployment exemption for you. There is no need for taxpayers to file an amended return unless the calculations make the taxpayer newly eligible for additional federal credits and deductions not already included on the original tax return.

[NCperson]

@Mooby the "problem" ocurred because Congress passed the American Rescue Plan Act of 2021 which became law on March 11, 2021.  That law eliminated the first $10,200 of unemployment income from being taxable.  By that time many had already filed and required the IRS to adjust millions of tax returns.

So if you reported unemployment income and filed before March, you didn't get the benefit that Congress afforded you.  

did you report unemployment income?