Do you have to pay income tax on money earned while working after age 72?

Sure and you already know that you will have to do this. Age is NOT one of the requirements of when a person MUST FILE A INCOME TAX RETURN. When you have the amount of taxable income for your filing status to meet the MUST FILE A INCOME TAX RETURN you can be any age as long as you are still breathing you will be required to file your 1040 income tax return correctly and pay the amount of income TAX that may be due on all of your gross taxable worldwide income.