Examples
Examples
Try the starting example
- Invoice lines: name, tax-exclusive net $, entered tax rate %
- A,0.03,20 B,0.03,20
- Tax rounding: line or rate-group
- line
- Total tax-exclusive net ($)
- $0.06
- Tax total under selected rounding ($)
- $0.02
- Tax-inclusive invoice total ($)
- $0.08
- Tax by entered rate group ($)
- 20%: 0.02
- Line-rounded minus group-rounded tax ($)
- $0.01
Try another scenario
- Invoice lines: name, tax-exclusive net $, entered tax rate %
- A,0.03,20 B,0.03,20
- Tax rounding: line or rate-group
- rate-group
- Total tax-exclusive net ($)
- $0.06
- Tax total under selected rounding ($)
- $0.01
- Tax-inclusive invoice total ($)
- $0.07
- Tax by entered rate group ($)
- 20%: 0.01
- Line-rounded minus group-rounded tax ($)
- $0.01
Calculation method
Calculation method
Total tax-exclusive net ($)
Sum exact-cent net lines.
Tax total under selected rounding ($)
Line: round each line tax. Rate-group: combine net lines with the same numeric rate, then round once per group.
Tax-inclusive invoice total ($)
Net+selected tax.
Tax by entered rate group ($)
Show each rate group’s selected rounded tax.
Line-rounded minus group-rounded tax ($)
Compute both methods on the same lines and subtract group-rounded tax from line-rounded tax.
Symbols and units
- a
- Invoice lines: name, tax-exclusive net $, entered tax rate %
- b
- Tax rounding: line or rate-group
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions & limits
Assumptions & limits
- Compares two explicit half-up rounding models on non-negative net invoice lines. Rates are user supplied; this is a reconciliation comparison rather than a statement of tax compliance.
Are these inputs private?
These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.
Further reading
HMRC: tax fractions, invoice rounding and credit-note background; rules vary ↗
Background reading; this does not imply endorsement or independent review of SumFizz.