A Structural Deficit is a mainstream term. But WTF is it? Does it really exist?
Government finances are structured such that tax revenue plummets during recessions (taxing profits and incomes). It is therefore normal for a deficit to appear temporarily. When profits and employment recover, the budget of the government should return to the black.
If instead deficits persist after a recovery, or there is no recovery, then there is a structural deficit in the structure of the budget.