Sinking fund
Money set aside a little at a time so a known future expense — a roof, an HVAC system — is a withdrawal, not an emergency.
A sinking fund is a savings pot you build gradually for a large, predictable cost you know is coming but haven't incurred yet. For a homeowner, that's the eventual roof, HVAC system, water heater, or repipe — each a four- or five-figure replacement with a fairly knowable [service life](/glossary/service-life). Instead of being blindsided, you divide the expected cost by the years until you'll likely need it and save that amount monthly into a separate account. It's distinct from your day-to-day maintenance budget (which covers filters, flushes, and small repairs) and from an emergency fund (which covers the unexpected): a sinking fund is for the big, scheduled-but-not-yet-due [capital expenses](/glossary/capital-expense). Pairing a per-square-foot maintenance budget with a dedicated sinking fund is the cleanest way to keep both routine upkeep and the occasional big-ticket replacement off your credit card. Our [home maintenance budget calculator](/guides/home-maintenance-budget-calculator) sizes the routine half of that picture, and the [home repair sinking fund calculator](/guides/home-repair-sinking-fund-calculator) sizes the big-replacement half — one monthly number per system.