In my property settlement when I divorced in 2014, in exchange for giving up equity in my home and more than 1/2 of community property, including approximately $50,000, my ex was to pay all back taxes (approximately $75,000) He has not paid this and now the IRS is coming after me. I thought I remembered that there was a provision that prevents IRS from taking any monies out of my SS since it is myonly source of income.

Yes the Federal government may garnish social security for unpaid taxes.

Presumably you have the official divorce agreement in writing. A tax attorney can help you out of this. (Can't believe you agreed to it unless he had a lawyer and you didn't!)