If I enter an already used w2 can you alert me of the error. I can't remember if I filled it last year it not. Please help

[mz-mines-nm]

Will you tell me if w2 has been used on previous return?

[Critter]

Not sure what you mean ... you can only put 2018 income on a 2018 return, 2017 on a 2017 return, etc.

[VolvoGirl]

Did you file a 2017 return?  If you didn’t include a W2 on a prior year return you will need to amend that year to add it.  Better print out your prior return and see if it’s included on the Wages line.

[xmasbaby0]

No.  The software will not know if you already used a W-2.  TurboTax is software for a do-it-yourself tax return.  Look carefully at your W-2.  It has the year on it.   You should not be entering a W-2 from any other year in to your 2018 tax return, if that is what you are working on.  And employers have not even issued 2018 W-2's yet--they are issued in January.  Please explain what you are trying to work on.