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TaxExclusive

Function TaxExclusive( aValue, aTaxRate : Extended) : Extended

Example​

procedure ScriptEvent(var Value: Variant);
begin
  Value := TaxExclusive(115, 15); // 100
end;

Usage​

TaxExclusive removes a percentage tax factor from a tax-inclusive value without rounding.

Parameters

NameTypeDescription
aValueExtendedTax-inclusive value to convert.
aTaxRateExtendedIncluded tax rate expressed as a percentage; for example, 15 means 15%.

Returns

An Extended result equal to aValue / ((aTaxRate + 100) / 100). The result is not rounded.

Behaviour

A zero rate returns the supplied value. The function does not inspect tax codes, jurisdiction, effective dates or configuration; the script must supply the applicable rate.

Errors

There is no local validation or exception handler. Any arithmetic exception raised by the active floating-point environment propagates to the script runtime. The function does not test for or replace non-finite results when floating-point exceptions are masked.

Additional Technical Info​

TaxExclusive removes a percentage tax factor from an inclusive value and returns the corresponding tax-exclusive base.

Implementation

The Velox scripting import registers the numeric function directly. The terminal implementation adds 100 to the percentage, divides that sum by 100 to form the inclusive factor, then divides aValue by that factor.

Edge cases and quirks

  • aTaxRate = -100 makes the factor zero and attempts floating-point division by zero. Depending on the active floating-point exception mask, this can raise an exception or produce a non-finite value.
  • Rates below -100, negative values and rates above 100% are accepted and processed literally; the function does not decide whether they are commercially meaningful.
  • This is not equivalent to subtracting TaxAmount(aValue, aTaxRate) from an inclusive value, because the percentage base is different.
  • Binary floating-point Extended arithmetic can produce a result slightly above or below the decimal value expected. No currency rounding occurs, and the type's representation varies by platform.

Performance and concurrency

The calculation is constant time, allocation-free and has no shared-state side effects.

Remarks

Subtract the returned exclusive value from the original inclusive value if the mapping needs the embedded tax component. Apply the destination's approved currency rounding rule after the calculation.

Related entries

  • TaxInclusive — applies the inverse percentage factor to an exclusive value.
  • TaxAmount — calculates a percentage of an explicitly supplied base.

External references

Created 2026-07-15