if i buy a home can i change my w4?

Answer 1

yes you can change it as long as you pay your taxes when they come due on April 15 but since you will be having a mortgage you will get a a write off on the interest and come out even.With the IRS is either pay now or later its your choice

Answer 2

You are allowed by law to change your W4 anytime you want, as often as you want, as long as you are not committing fraud by claiming more exemptions than you are entitled to.

If you start changing it all the time, don't expect HR to process it very quickly after the first time or two.