How do I sign my returns?

[DoninGA]

If you are e-filing the tax returns there is no physical signature on the Form 1040,  The 2021 AGI you entered is your electronic signature.

[Critter-3]

Actually you pick a 5 digit number to be your efile signature  ... the prior year AGI is to confirm this is you when using a DIY program.   When using a professional program the prior year AGI is not needed at all.  

[TerukoL]

During the filing process in TurboTax, you will be asked for either your prior year adjusted gross income (AGI) or your prior year PIN. The AGI or the prior year PIN serves as your signature on an e-filed tax return.  

Please click the following links to learn more:

Is my Self-Select PIN the same as my IP PIN?

How do I e-file my personal (individual) tax return?