What does your Dr.H use for purchasing power?

I've got a money question for all ya'll med spouses out there. How do you work debit cards, etc?

My husband wants a debit card so that he can buy things. I understand his desire. My question is if he's debiting and I'm debiting, how do we know how much we have to spend in the account?

Do your dr.h's carry credit cards? Cash?

How do you work this out? I would appreciate any ideas.

I am trying to revamp our finances to get us living within our means.