Foreign-Exchange Scarcity, Monetary Financing, and Informality: A Hybrid Stock-Flow-Consistent Framework with Import Rationing and Fiscal Feedbacks

Algeria offers an unusually demanding setting for macroeconomic modeling because the same hydrocarbon shock can reach the balanceof payments, the budget, money creation, domestic supply and the informal economy at the same time. This article develops a hybrid stock-flow-consistent (SFC) model built around that interaction. Exact monetary and expenditure identities are combined with an annual nonlinearrecursion for hydrocarbon receipts, public revenue, foreign-exchange availability, import rationing, external debt service, reserves, monetaryfinancing, inflation, the parallel-market exchange-rate premium, capital flight and cash-intensive informal activity. The starting stocks aredrawn from official 2024 monetary data, while the central macro path for 2025-2031 is anchored to the IMF 2026 Article IV estimates andprojections. The years 2032-2035 are model extensions and are not IMF forecasts. A hard foreign-exchange constraint is imposed: importsactually paid for in foreign currency cannot exceed usable external resources. When that constraint binds, intermediate and essential inputsreceive priority over capital and consumer goods. Informality is not equated with currency holdings; it is represented as a latent monetaryblock based on excess cash demand, parallel-market pressure and formalization, with its reported share defined relative to total modeledactivity. Three conditional paths are examined: baseline, persistent stress, and adjustment/formalization. Under stress, weaker hydrocarbonearnings tighten both the external and fiscal positions; import shortages lower productive capacity; inflation and exchange-marketsegmentation intensify; and capital flight and informality reinforce the loss of buffers. The accounting identities close to numerical precision.Sensitivity tests also show that the direction of the stress mechanism is robust, although the terminal levels of reserves, the exchangepremium and informal activity remain parameter-sensitive. The main contribution is therefore not a point forecast. It is a transparent, testabletransmission structure that can be estimated and validated once a longer historical database is assembled