A mid-year fix still works
Discovering a shortfall in October doesn't mean waiting for next year — concentrating the catch-up into your remaining paychecks (fewer periods left, so a larger amount each time) still lets you close the gap by April. A large bonus can throw this off on its own; see the Bonus Tax Calculator for that piece.
Frequently asked questions
Where do I get my estimated total tax liability?
Run your expected annual income through the Income Tax Estimator (or your prior year's return as a starting point, adjusted for changes) to get a number to enter here — this tool focuses on reconciling that liability against what is actually being withheld, not computing the liability itself.
Why does a bonus matter for withholding?
Bonuses are usually withheld at a flat supplemental rate that often doesn't match your actual marginal rate — see the Bonus Tax Calculator for that piece specifically. Include the bonus in your annual income estimate here so the year-end reconciliation accounts for it.
What if the suggested amount is negative?
A negative number means you're on track to overwithhold — you could reduce withholding instead (a bigger paycheck now, smaller refund later) rather than adding more.
Last updated: June 2026