I don't think the protocol broadcasts remaining balance as a transaction, but I might be wrong.
Yeah, it does. Due to the way the technology works, you have to spend all of the money you got from a previous transaction. So if you ever got 500k in one transaction, you have to take all that, send 1BTC to someone, and send the 499 999 BTC to a new wallet address. Or if you use a custom client: to the same address again.