Before tax
=IFERROR(IF(AND(ISNUMBER(A2),ISNUMBER(B2),A2>=0,A2<=1000000000,ROUND(A2,2)=A2,B2>=0,B2<=1000,ROUND(B2,6)=B2),ROUND(A2,2),NA()),NA())FORMULAS · MANUAL PERCENTAGES
Tax Formula Generator
One manually entered percentage. No official tax rate or category is selected.
Amount: up to 2 decimals. Percentage: up to 6 decimals. Non-negative values only.
Output format
Worked example
2 decimals · Half-up roundingBefore tax
Tax amount
Total including tax
100.00 + 8.00 = 108.00 GBP
Generated output
Tax amount
=IFERROR(IF(AND(ISNUMBER(A2),ISNUMBER(B2),A2>=0,A2<=1000000000,ROUND(A2,2)=A2,B2>=0,B2<=1000,ROUND(B2,6)=B2),ROUND(A2*(B2/100),2),NA()),NA())Total including tax
=IFERROR(IF(AND(ISNUMBER(A2),ISNUMBER(B2),A2>=0,A2<=1000000000,ROUND(A2,2)=A2,B2>=0,B2<=1000,ROUND(B2,6)=B2),ROUND(A2+ROUND(A2*(B2/100),2),2),NA()),NA())Rounding and scope
In add mode, tax is rounded before being added. In extract mode, the net amount is rounded and tax is the remaining difference. These are manual arithmetic rules, not country-specific legal rounding.
Input caps, not legal limits: amounts up to 1,000,000,000 for spreadsheets or 1,000,000,000,000 for decimal code; percentages from 0 to 1,000%.
Spreadsheet cells must contain numeric values. Decimal separators, function names and argument separators depend on workbook settings. Spreadsheet numeric precision can differ from decimal arithmetic; use decimal code for precision-sensitive workflows.
Code inputs are decimal strings with a dot separator; the rate is in percentage points. JavaScript uses decimal.js. Python uses the standard-library Decimal type.
No exemptions, multiple tax components, discounts, filing advice or compliant invoice rules are inferred.
Technical references