"But no one answered straight to the question if I should file separately 940 and W-2's for new owner starting 5/1/2021 and one for the period 1/1/2021 - 4/30/2021 under the old owner or just file one 940 and W-2's for the whole year."

Yes, everyone pointed out there is no carryover.

You cannot file W2 without a different EIN, and you cannot use the same EIN for the whole year, for all of this is a mess.

The 940 is an Annual form, for wages taxed only up to the first $7k, and now you have Two businesses to contend with, as the new owner started with Payroll in May at $0 YTD. The old owner is the 940 up to the final paydate under that person's ownership.

This topic is dead, because the picture is horrible.