I am CND military living abroad temporarily, still employed by DND. My T4 says ZZ. My husband also Military is working remote but T4 says ON. Any pointers?

You would first need to determine your and your spouse's residency status. It's likely that you would either be factual residents or deemed residents. This Canada Revenue Agency (CRA) page can help you determine your residency for tax purposes: https://www.canada.ca/en/revenue-agency/services/tax/international-non-residents/information-been-moved/determining-your-residency-status.html