Is your W-4 right? Avoid a tax bill — or stop over-withholding and losing interest.
TurboTax W-4 calculator provides personalized, precise withholding guidance for your exact situation.
Try TurboTax W-4 Calculator →Over-withholding: You loan the IRS money interest-free all year. A $2,000 refund in a 4.5% HYSA would have earned $90 for you instead.
Under-withholding: Risk owing at filing plus an 8% underpayment penalty if you owe $1,000+ and paid less than 90% of your tax liability.
Sweet spot: Owe $0-500 at filing. Keep your money working all year and avoid penalties.
Get Form W-4 at irs.gov, fill it out, and submit to your employer's HR. You can change it anytime. Use Step 4(c) to add a specific extra dollar amount per paycheck.
If you owe $1,000+ at filing AND paid less than 90% of current-year tax (or 100% of prior-year tax). 2025 rate: 8% annualized on the shortfall amount.