Origin: Latin suffix -able
Taxable has 3 different meanings across 1 category:
Something on which tax must be paid.
"The inheritance she received was fully taxable, so she had to pay a portion of it to the government immediately."
In plain English: A taxable is an amount of money that you must pay to the government as tax on your income, sales, or other earnings.
"The taxable refers to the amount of income subject to tax this year."
subject to taxation.
"The company received an invoice for taxable income that must be reported to the government."
The word taxable is formed by adding the suffix -able to tax. It entered English as a straightforward compound meaning something that can be taxed.