how to calculate tax inclusive

[Guest]

What formula do I use to calculate tax that is included in the gross amount?

 

[Guest]

Say you have your tax % in cell A1 and your inclusive amount in C5. In C6
enter
=C5-(C5/A1)

 

[vandenberg p]

: What formula do I use to calculate tax that is included in the gross amount?

An argument for why simple algebra is important

Let $T = amount of tax
let i= tax rate
let x = inclusive amount
let y = amount exclusive of tax
x = y + t*y
x = y*(1+t)
x/(1+t) = y
$T = x - y
or in one formula:
$T = x - x/(1-t)

Example:

Row/Col A B
20 t= 0.05
21 x= 1
22 $T = 0.047619048

Formula in B22:

=B21-B21/(1+B20)

Pieter Vandenberg