What is the name of your state (only U.S. law)? TN
My husband has paid his back alimony and now his ex is saying that he owes more and is wanting to charge interest. Can she do that?
First of all, it is not HIS alimony, it is HER alimony.
Your statement is a little contradictory because if he has paid her back alimony, how can he owe more?? And if he does indeed owe more, then he hasn't paid her back alimony, at least not all that he owes.
If there is outstanding alimony then yes, she is well within her rights to demand interest. She will bleed him to death just like a credit card company if he doesn't pay what is expected of him.