How do your clients feel about getting increasingly threatening notices from IRS all summer?
(And it sounds like this is a joint return, which are the last that will be reviewed.)
Some are waiting for Commissioner Rettig to come down from the mountain with "guidance" on tablets telling us whether to amend returns for this new exclusion, in some cases like this one, where a balance due turns into a refund. I would file an amended return, now. Will you have to do that for the state, anyway?