It's a little more complicated than dollar for dollar and so I'll start and then turn to Finance.
When departments are resourced through their appropriations, which is on a modified cash basis, and that's what Parliament votes on, we have to translate that into accrual dollars. If I'm buying a tank, while it might cost me $1 million this year, I know from an accrual perspective it's going to cost me a portion of that over the next 10 or 15 years. There's an accrual translation that's made.
The more important point for my colleagues in Finance is they know departments are not going to spend every dollar that Parliament votes, so they build a lapse into the overall fiscal framework. Where a department's actual results differ from their assumptions, then you get a dollar-for-dollar pick-up. I'm not sure if Finance wants to add anything on how they forecast for expenses.