Every year my spouse and I make up our budget. We decide what we expect to pay for food, housing, utilities, clothing, transportation, recreation etc. etc., what we hope to be able to save, what we'll give to charity, etc.
We try to stick to that budget but never can do so exactly. Sometimes we have to move budgeted monies from transportation or recreation or some other fund to cover an unusually high utility bill or an unexpected plumbing bill or whatever.
At the end of the year, if we have more money in investments, savings, and checking account than we started with, we enjoy a surplus. If we have less money in investments, savings, and checking account than we started with, we have a deficit.
The budget doesn't have a dang thing to do with any of that other than providing a guideline for us to follow. It's writing checks against what we deposit that determines whether we have a surplus or deficit.
Look, I know what you're saying. It still doesn't contradict the fact that the amount you are short can equal 1/3 of what you budgeted in the first place, which was my point.
And if part of your budget was mortgage payments, car payments etc, you have to pay them off, or lose your house and your car. You also would have to pay off maintenance costs, etc, that you would have budgeted for originally.
If, halfway through your budget year, your wife loses her job and cuts your income in half, then the deficit is going to be much larger than expected, if you stick to your budget.
The spending is already budgeted. In the government's case, it can borrow the money to make up the difference between what it budgeted and what the actual revenue figures are, or it can fire a bunch of people that are currently working for them, or cut benefits to below what people expected based on the Budget.
In our current case, if you budget a wage increase for Soldiers serving in Iraq, you can't just take it back halfway through the year, if you budget involves an increase in the amount of people receiving social security, you can't just not pay those people, and if your Budget does not account for a massive unexpected shortfall in tax revenue, you can't just suddenly stop covering Medicare.
I mean, you could, but it would be really really bad.