Business tax / Free financial tools

Estimated Tax & Reserve Calculator

Compare projected annual tax with payments and estimate the cash reserve still needed.

US federal • 2026 · Instant results · No sign-up

Enable JavaScript to use this interactive calculator. The calculation method and assumptions are explained below.

How this calculator works

Projected balance equals annual tax minus withholding and estimated payments. The ordinary safe-harbor model compares 90% of current-year tax with 100% or 110% of prior-year tax. Monthly reserve divides the remaining positive balance by months left.

Planning estimate only. Review the assumptions alongside the result before using it for a tax, financing or business decision.

IRS estimated taxes

Common questions

Is this the payment due this quarter?

No. Installment timing, withholding allocation and annualized income can change the payment needed. The output is an annual planning target, not a penalty-safe payment instruction.

Can I owe a penalty despite a refund?

Yes. Underpayments during earlier installment periods can matter even if year-end payments exceed the final annual tax.

Put your numbers into context.

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