Can I amend my return next year if I forgot a w-2 or do I have to do it this year?

The 2024 W-2 can only be entered on the 2024 tax return.  You will need to amend the 2024 tax return you filed to add the W-2.

Before starting to amend the tax return, wait for the tax refund to be received or the taxes due to be paid and processed by the IRS.

See this TurboTax support FAQ for amending a current year tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-federal-tax-return-current-year/L7eS6o1qh_US_en_US?uid=lfunevhk

No, you can't add a 2024 W-2 to your next year's tax return.  You need to amend your 2024 tax return and add your W-2.

You have to file an amendment but wait until your tax return is fully processed and you receive your refund or your balance due is deducted from your account.  When you do your amendment to add your W-2, TurboTax will calculate your new refund or balance due based on your additional income. If your original refund was more than what you should have received when your W-2 is added, you will have a balance due.

For more information and instructions, review the TurboTax articles How to Correct Federal Tax Returns, How to File an Amended Tax Return with the IRS and Video: How to Amend Your Tax Return.

@maxinelucci