Tithe is to be based on INCREASE, not income.

Thou shalt truly tithe all the INCREASE of thy seed, that the field bringeth forth year by year. Deuteronomy 14:22

At the end of three years thou shalt bring forth all the tithe of thine INCREASE the same year, and shalt lay it up within thy gates: Deuteronomy 14:28

Increase means additional net worth.

INCREASE is NOT INCOME.

Most Israelites didn't have income. They ate daily from their herds and gardens and purchases. What they consumed daily did NOT count as INCREASE. Today we might call that daily consumption "income" or its analog, but it wasn't increase. The tithe was calculated solely on increase.

Abraham is the first Bible example we have of any tithe, and that was only a single instance in which he gave 10% of his spoils of battle to Melchizedek, king and priest. (Genesis 14:20)

Abraham didn't just have a thousand cattle, he had cattle (many) on a thousand hills! Every year he had more. We don't know if tithe was even implemented at the time of Abraham, but if it were, based on our Biblical instruction, the "more" was his increase. If he had 10,000 cattle one year and 12,000 cattle the following year, his increase was 2000 cattle. 10% of that would be 200 cattle. These were to be set aside for a feast. Abraham never had income, only increase. He didn't work for wages. He had servants and he paid them wages. What tithe did his servants pay? None on their income. Only if they had fields and if they had an increase from those fields, would they pay tithe.

Demanding tithe based on income is the biggest fraud in Christianity today.