I filed an extension to form 1040 on April 11, 2025 and received confirmation back that it was accepted. Just received notice that my return is late. Need copy of ext.

It seems that the IRS itself has some sort of glitch that is triggering these notices to go out unnecessarily.    You should be safe to ignore it and just get your return filed by the October 15 deadline.   We have been seeing some other posts from users who received these notices.

@saminick See this in another thread:

https://ttlc.intuit.com/community/taxes/discussion/re-filed-2024-extension-extension-approved-then-received-irs-letter-saying-i-didn-t-file-this-is-the/01/3694007#M1366043