“It’s not that I’m doing better than you, it’s just that I AM better than you.” - People that be like that sometimes.

1. No, take out taxes as normal and do not allow an adjusted W-4 unless employee has a specific life event that would necessitate such a move (discovered wrong # of exemptions, got married, had kids/adopted, got divorced, other sort of changed filing status, or maybe some of those random farming and clergy items that us regular folk never get to do)
2. If it’s a good, reliable employee that is on hard times or short on funds for a specific thing, you could always front a portion of their next paycheck by adding it to the current paycheck (including paying the appropriate amount of taxes) and then adjust down the next paycheck.
3. Give them an early Christmas bonus (and be sure to take out the proper amount of tax, lol)