[lewislynn]

You think there's no such thing as tax exclusive rate, and you insist on using the tax exclusive rate.

Not for income tax. An "exclusive tax rate" on, of, or against income isn't possible.

Shall I continue?

Continue making a fool of yourself over this nonsense? Who's stopping you?

[Principled]

An "exclusive tax rate" on, of, or against income isn't possible.

Not in your feeble mind perhaps. But here it is... don't melt!

Earn $100,000 and keep $80,000 after tax. You can figure the rate more than one way silly.

1) amount of tax divided by the total INcluding tax (ie tax inclusive); 20k/100k=20%
2) amount of tax divided by the amount remaining EXcluding tax (tax exclusive); 20k/80k=25%

There is no one way to figure percentages. Both rates above are correct obviously. You can use either you wish.

Really, why do you get into the math anymore?