Probably a decimal point.... i.e I I need to put in a .
IF it is a number field, just delete the whole entry and retype it being careful to not hit the comma key.
Still, in some areas, the software will round the numbers per IRS instructions, but the software W-2 form itself allows decimal entries.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*