In 2015 my then 76 year old wife earned $53,000 in additional income (fee for aacting as executor of her aunt's estate ). Does she have to pay social security tax on that money at her age ?

You can report it as other income on Form 1040 line 21. Here's how to enter it in TurboTax.

• Click the Federal Taxes tab ( Personal in the Home & Business version)
• Click Wages & Income. (Personal income in the H & B version)
• Click "I'll choose what I work on."
• On the screen "Your 2015 Income Summary," scroll all the way down to the last section, "Less Common Income."
• Click the Start or Update button for the last topic, "Miscellaneous Income, 1099-A, 1099-C."
• On the next screen, "Let's Work on Any Miscellaneous Income," scroll down and click the Start or Update button for the last topic, "Other reportable income."
• The next screen asks, "Did you receive any other taxable income." Click Yes.
• On the next screen, "Other Taxable Income," enter a description and the amount. Click Continue.
• On the next screen click Done.

The income will be reported on Form 1040 line 21 with the description that you entered.