Can I file a return for 2024 after April 15th if I do not owe?

If you do not owe or are getting a refund there is no penalty for filing after the April 15 deadline.  You will be able to e-file up until October 15.  

Where do I find my AGI?

https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/01/25947

Your 2023 tax return shows your 2022 Adjusted Gross Income  (AGI)  If you filed a joint return then the AGI is the same for each of you.

Form 1040        line 11

If entering the amount from your 2023 tax return does not work, then try entering “0” instead.  If that does not work and you still cannot e-file, then print, sign, and mail your tax return.

You can get a free transcript of your past return from the IRS:  

https://www.irs.gov/individuals/get-transcript

Note: If you filed late or amended your return, your correct 2023 AGI may not be in the system. 

A 2024 tax return with a tax refund can be filed at any time on or before April 15, 2028.

The TurboTax 2024 online editions will be available up through October 15, 2025.  After that date the TurboTax 2024 desktop editions can be used.