If I find a transaction that was recorded incorrectly in QuickBooks, can I change it even after paid 1st Q est tax?

Hello there, @cesar-amendes90-.

Allow me to share some details about the process if you want to make changes to your transactions within the 1st quarter.

You can change the transaction that is dated within the quarter if you haven't filed your tax yet. However,  if you want to make changes after the original tax return has been filed, you must file an amended tax return using a special form called the 1040X. You'll need to enter the corrected information and explaining why you are changing what was reported on your original return.

I've added an article to know more about amending self-employed tax: Amending Your Income Tax Return.

I'll be around if you have other questions. Just click the Reply button and enter your concern. Take care.