If you were unpleasantly surprised by the amount of tax you owed or the amount of your tax refund when you filed your 2018 tax return, it may be time to check your withholding.
It may also be time if there are changes in your life or financial situation that affect your tax liability. For example, have you recently married, divorced, had a child, purchased a new home, changed jobs, or had a change in the amount of your taxable income not subject to withholding (e.g., capital gains)?
You can generally change the amount of federal tax you have withheld from your paycheck by giving a new Form W-4 to your employer. You can use a number of worksheets for the Form W-4 or the IRS Withholding Calculator (available at irs.gov) to help you plan your tax withholding strategy.
If changes reduce the number of allowances you are permitted to claim or your marital status changes from married to single, you must give your employer a new Form W-4 within 10 days. You can generally submit a new Form W-4 whenever you wish to change your withholding allowances for any other reason.
In general, you can claim various withholding allowances on the Form W-4 based on your tax filing status and the tax credits, itemized deductions (or any additional standard deduction for age or blindness), and adjustments to income that you expect to claim. You might increase the tax withheld or claim fewer allowances if you have a large amount of nonwage income. (If you have a significant amount of nonwage income, you might also consider making estimated tax payments using IRS Form 1040-ES.) The amount withheld can also be adjusted to reflect that you have more than one job at a time and whether you and your spouse both work. You might reduce the amount of tax withheld by increasing the amount of allowances you claim (to the extent permissible) on the Form W-4.
You can claim exemption from withholding for the current year if: (1) for the prior year, you were entitled to a refund of all federal income tax withheld because you had no tax liability; and (2) for the current year, you expect a refund of all federal income tax withheld because you expect to have no tax liability.