Section 31. Automatic Appropriations. —

All expenditures for (a) personnel retirement premiums, government service insurance, and other similar fixed expenditures, (b) principal and interest on public debt, (c) national government guarantees of obligations which are drawn upon, are automatically appropriated: provided, that no obligations shall be incurred or payments made from funds thus automatically appropriated except as issued in the form of regular budgetary allotments.