How does the refund estimate work?
The calculator estimates regular federal income tax using 2026 ordinary-income brackets, subtracts entered nonrefundable credits, then compares that tax with the federal withholding and estimated payments you enter.
What does a positive refund estimate mean?
It means the entered federal payments exceed the estimated regular federal income tax included in this simplified model. A negative balance means the estimated tax is higher than the entered payments.
Why can the filed refund differ?
Real returns can include refundable credits, self-employment tax, Additional Medicare Tax, capital gains, AMT, NIIT, penalties, special deductions, dependents, prior-year items and many other rules not collected here.
Does Social Security and Medicare withholding increase my federal income tax refund?
Ordinary employee Social Security and Medicare taxes are separate payroll taxes and are not treated as federal income tax withholding in this refund comparison.
Frequently asked questions
Sources and methodology
The calculator uses the current federal figures or official agency guidance described below where those rules apply. State-specific results should always be checked with the relevant state tax authority.