How come the last check of the last year does not apply to 2017 but instead since it was received on the 4th of Jan. it counts for 2018???

[psycon5]

The ending pay date was the 30th of December but got paid on the 4th of Jan.

[VolvoGirl · Accepted solution]

It's not when you actually worked but when you got paid.  Tax returns go by the year you got the payment or cash.

But then the first check of the year you got back in Jan 2017 (a year ago) would have been for Dec 2016.  So it all works out.  

[xmasbaby0]

Whatever your W-2 says is what matters.  If your last paycheck was dated January 4, 2018, then that was pay received in 2018 and you will enter it on your next year's return.

[Critter]

Because that is the way the payroll rules are written.