Well, this is one of the issues that I do disagree with Leon on

I think for some people that keeping separate accounts IS a good, and perfectly healthy option. I actually prefer having yours, mine and ours accounts.
Some of this depends on personalities. If you have a spender, and a saver, allowing each person to have a small checking account with a debit card can be good for both. (this is how I take my pocket money, in my checking for my debit card. I’ll save up to buy something, larger even though I give DH more pocket money.) As he will spend every cent that he has at his disposal. When I allowed him to have more and more and more money because he spent all of his pocket money on Mt Dew and chips, and denied myself pocket money, I got resentful. I know people who have remarried, and have adult children. If they keep some of their money separate, if the husband gives his daughter money for an apartment security deposit, his wife has nothing to say, like, “AGAIN!?!??!” If the daughter doesn’t pay back, it’s just his loss, not THEIR loss. The same is true if the wife lends, or gives money to one of her adult children.