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TaxAmount

Function TaxAmount( aValue, aTaxRate : Extended) : Extended

Example​

procedure ScriptEvent(var Value: Variant);
begin
  Value := TaxAmount(200, 15); // 30
end;

Usage​

TaxAmount calculates a percentage tax amount from the supplied base value.

Parameters

NameTypeDescription
aValueExtendedBase value on which the percentage is calculated.
aTaxRateExtendedTax rate expressed as a percentage; for example, 15 means 15%.

Returns

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

Behaviour

The function performs no tax-code lookup and does not know whether the input includes tax. It calculates only a percentage of that input. A zero rate returns zero.

Important usage notes

  • Do not use this formula to extract the embedded tax from an inclusive total. For example, 15% of an inclusive total is not the 15% tax component originally added to its exclusive base.
  • Negative rates and values are accepted and affect the result's sign. Rates above 100% are also calculated literally.
  • The Extended calculation is binary floating-point and is not rounded to a currency scale. Its precision and storage are platform dependent.

Usage notes

Use TaxInclusive for the total after adding tax. If starting from an inclusive total, use TaxExclusive to obtain the base and subtract that base when the separate tax component is needed.

Additional Technical Info​

TaxAmount calculates a tax percentage of the value supplied by the script. Pass a tax-exclusive base when the required result is the tax that would be added to that base.

Implementation

Velox exposes the implementation directly through its number-functions scripting import. The terminal function converts the rate to a fractional multiplier, multiplies it by aValue, and returns the result unchanged.

Errors

No rate validation or exception translation occurs. Arithmetic failures raised by the runtime propagate to the script.

Performance and concurrency

The function is constant time, allocation-free and independent of shared Velox state.

Related entries

  • TaxInclusive — adds the percentage factor to an exclusive base.
  • TaxExclusive — removes the percentage factor from an inclusive value.

External references

Created 2026-07-15