Are you married and both spouses work? Multiple changes to the withholding tables have made it more important to regularly check your W4 for federal withholdings. If you are married and your spouse works, you both should claim single on your respective W4 to have the correct federal tax withheld.
If you choose married, the withholding tables assume you get the married standard deduction.
If both you and your spouse claim married, you are doubling the standard deduction which doesn’t happen and you end up short on your withholdings.