ask your payroll department, but assume it will be a 2020 income. When you receive your 1/1/21 paystub, look at the year to date amounts. Did they reset? Probably not.
how do know that paystub will be dated 1/1/21 and not 12/31/20? or are you just assuming?
As others posted, wait for the W-2 to populate Turbo Tax as that will eliminate issues later.
