Hi Figbar,
Allowances can be excludable and makes sense in your particular case. To pay your fair share of taxes and no more, Complete Step 1 and Step 5 of the W-4. Step 4 allows you to increase the $$$ amount taken from your check each pay period. Single filers should always consider before tax contributions such as 401K, 403B, Flexible spending accounts, and 125 Cafeteria plans when available.
Good Luck to you!