Ideally it should be balanced. We haven't had that since 2000.

When there is a shortfall, it leaves a deficit. Somebody who was suppoed to be paid for services or products doesn't get paid in time. They have to wait for the next annual pay cycle. Republican cutting taxes is exactly the WRONG thing to do. That makes the deficit larger. That means more poople who are supposed to be paid on time won't be. Interest accrues on the deficit as an incentive to pay on time. Most of the time it is tacked onto the deficit, making that grow ever larger.

Democrats traditionally pay down the deficit with more spending, which the GOP says is wrong. Republicans increasw the deficit by cutting taxes, but spending just as much and sometimes more. They bank on most Americans not paying close enough to their own finances to notice or be concerned.