Life-Cycle Hypothesis Model

The Life-Cycle Hypothesis, associated with Modigliani and Brumberg and later aggregate tests by Ando and Modigliani, treats saving as a way to move resources across age.

Workers save during high-earning years and retirees draw down wealth. The model explains why age structure matters for aggregate saving, asset demand, pension design, and fiscal incidence.

The baseline route assumes certainty and no bequest motive to show the core geometry. Real households face longevity risk, health shocks, housing illiquidity, and family transfers.

Lifetime resources equal initial wealth plus labor income during working years. The household divides those resources over the full planning horizon.

Saving is positive during work if annual income exceeds smoothed consumption. It becomes negative in retirement when labor income stops.

Longer retirement lowers annual consumption unless work years, income, returns, or initial wealth rise. That is the central demographic pressure in the model.

Pension policy uses life-cycle logic to ask how benefits, retirement ages, and mandatory saving change private saving behavior.

Aging economies may save less as the retiree share rises, but the aggregate result depends on bequests, public pensions, labor-force participation, and asset returns.

The model is useful for household finance, but it should not be read as a literal forecast for households with credit constraints or uncertain lifespans.