State tax filing

My husband is tribal, I am not.  We live on the reservation in Wisconsin.  When filing our state taxes am I correct to say that I deduct his tribal per cap and any income from the tribe on our state tax return so we do not pay state tax on that money.  

Also, if I did not deduct it last year, what steps can I take to amend my state tax return from last year and possibly the year before that?