The difference between government spending and revenues over a very long term

The picture of a government deficit consists of two elements, a structural and a cyclical. In a state of depression at the lowest point in the business cycle, unemployment is elevated. This leads to reduced tax revenues and increased expenditures (e.g. on social security). On the other hand, at the peak of the cycle, unemployment is reduced; increasing tax revenues and reducing social security spending. Due to the borrowing in a state of depression, at the low point of the cycle, a cyclical deficit occurs. By definition, the cyclical deficit is refunded by a cyclical surplus at the peak of the cycle.
The structural deficit is an imbalance that occurs around the whole business cycle, since the general level of state spending exceed the prevailing tax levels. The structural deficit and the cyclical deficit or surplus sum up to a total budget deficit present.