Yes. We share absolutely every single thing with each other. There's nothing we don't trust each other with. I mean, I might not give him all the details about my private time in the restroom, but everything else is in the open. Yes, banking information, social security numbers, etc. it's all information we both know about each other. No big deal. I know for sure I can trust him with that stuff. I keep up with my money, he keeps up with his. I don't take/hold his money or keep up with his spending and same for me. I have what I earn, he has what he earns. No questions ever asked. Now he often times will pay for my things. Always usually. I might make a stop to Wal-Mart for nail polish or something and pay myself, but if he's with me, he almost always tells me to put it up and he'll hand his own money over. It's sweet. I buy him little things here and there and he's forever buying me things (not always so little either). So we do share, but we both pretty much have our own money, which I like. Nobody wants to be without and having to fully depend on the other.
If for any reason I could not trust him with my bank acct. money, I would not even be with him. We've been together for 6 years and I couldn't ever think of a reason to hide that info from him. I mean I guess if your partner had a spending problem (shopping/gambling addiction) I could see being cautious, but otherwise, it should be a trusting relationship.