The amount a taxpayer should have withheld from his paycheck depends on his filing status and the number of withholding allowances he can claim, according to the US Tax Center. Other factors that can influence the amount of withholding include marriage, divorce, new parenthood, and starting or stopping a job.
The Internal Revenue Service has an online withholding calculator that determines the amount a taxpayer should have withheld. To use the calculator, the taxpayer enters information such as filing status, gross income, the amount of federal tax withheld to date and the amount of tax withheld in the last paycheck. The calculator returns the amount the taxpayer should have withheld from checks for the remainder of the year to meet estimated taxes on earnings for the year.