Systematic Withdrawal Plans — Engineering a Reliable Retirement Income
A SWP converts a lumpsum corpus into a predictable monthly income stream while the remaining balance continues to compound at the underlying fund's return. It is the structural inverse of an SIP and forms the backbone of modern retirement and FIRE (Financial Independence, Retire Early) strategies.
The Formula
Each month: Bₘ = B_{m-1} × (1 + r) − W, where W is the withdrawal and r is the monthly return. The corpus survives indefinitely when the withdrawal rate is below the long-term return; it depletes when it isn't. The classic "4% safe withdrawal rate" derives from Trinity Study research on US equity-bond portfolios.
Sequence-of-Returns Risk
A negative return cluster in the first 5 years of withdrawal does disproportionately more damage than the same cluster mid-retirement. Hedge with a 2-year cash bucket plus a debt-bucket equal to 5–7 years of expenses.