Tax Invoice Supply / VAT / Total Checker

How it works

Not a 10% mental-math toy. Fill any one of supply, VAT, or total; the other two complete at 10%. With all three filled, the tool flags a typo if the sum or the rounding mode does not match—before you issue a Korean tax invoice or cash receipt.

1. Source field — the number you already trust.
2. Won rounding — round / floor / ceil, because bookkeeping apps disagree on the last won.
3. Fill the rest — from total, the total stays fixed and supply is total ÷ 1.1.
4. Mismatch — supply + VAT must equal total, and VAT must equal 10% under the selected rounding.

Copy the three numbers into chat or a quote. Browser-only; not a tax filing.

FAQ

Cash receipts too?

Yes for 10% taxable receipts. Zero-rated or exempt sales are not 10%.

Off-by-one won?

Your issuer may floor while this screen rounds. Match the rounding mode to the software you file with.