I filed 2023 electronically and it says it was been accepted. But when I go to file an amended return, it then says my return is late and won't electronically file it.

Your amended 2023 return cannot be e-filed.  You will need to print it, sign and date it in ink, and file it by mail.

 

Use a mailing service such as certified mail to track it so you will know it was received, since you will have a long wait for it to be processed.

 

 

Do not expect quick results from amending. It can take four months or more for the IRS to process an amended return.  

 

You can watch for information here:

https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1