MFS E-file rejection due to missing 1095-A on one spouse

Double check that he is not listed on his wife's 1095-A.

Ask him to call the Marketplace to verify he did not have insurance.  If he is a young person, he should verify his parents did not add him to their Marketplace insurance, or if he has a dependent on his return, he should verify nobody (such as a parent of the child that your client is no longer with) put the dependent on Marketplace insurance.

If all of that ends up as nothing, then type up an explanation indicating that he had no Marketplace insurance and verified that.  Then convert that to a PDF, attach that PDF as an "other" attachment and categorize it as "ACA Explanation".

If he did not have coverage in any month with Covered (State), then open the Form 1095-A and click the button at the top Check if no Marketplace Insurance Purchased.  Click on the button right below Quickzoom to ACA explanation quickzoom button and attach it as a pdf when you re-efile it again.

Interesting... I received a rejection today after selecting no coverage through marketplace and attached ACA Explanation.  

In your situation, you did it the way I would. Add the 1095-A with zero (0) percent on his return.  It should have not been rejected. Maybe mail the return.