if he waits past 10/15/25 to file his 2024 return it can no longer be e-filed. If he's due a refund it will be delayed possibly 6 to 8 weeks after the IRS gets it maybe even longer. I can't be sure. If he owes there will be penalties and interest for late payment and filing. If no extension is filed for 2024 and due a refund he could file as late as 4/15/2028. and get it. Miss the deadline and the iRS gets to keep any refund. There is no time limit if he owes. Penalties and interest continue to accrue.
