If I forgot to file my 2020 1099-NEC this tax year, can I report it on my taxes for next year? Or do I have to amend my taxes this year?

[Mike9241]

you'll have to amend. if you don't the IRS will eventually get around to sending you a bill for the taxes penalties and interest. do not amend until the IRS fully processes the original return. you have til 5/17 to pay any additional taxes without penalty or interest except possibly a penalty for underpayment of estimated taxes. 

[RayW7]

I agree with @Mike9241, The IRS will receive a copy of the 1099-NEC and try to match it to your return. 

-follow this link for information on filing an amended return-

How to File an Amended Tax Return with the IRS - TurboTax ...

How to Correct Federal Tax Returns - TurboTax Tax Tips ...