Short answer: A monthly stash for known future bills — insurance, school fees, festivals. It converts shocks into line items.
A sinking fund is a monthly amount set aside for a known, irregular bill — insurance renewals, school fees, festivals, car servicing, a planned trip. It converts a predictable shock into an ordinary line item, and it is the single most effective fix for budgets that work for ten months and collapse in two.
The problem it solves
Most budgets are built on monthly costs, while a meaningful share of annual spending arrives in lumps. Car insurance of ₹18,000, a ₹25,000 festival month, ₹40,000 of school fees and ₹12,000 of annual subscriptions total ₹95,000 a year — none of it a surprise, all of it arriving as one. Without a sinking fund these land on a credit card, and the interest converts a known expense into an expensive one.
How to size it
List the irregular costs you know are coming in the next twelve months, total them, divide by twelve. From the example above, ₹95,000 ÷ 12 is about ₹7,900 a month. That figure then sits in the budget as a fixed cost, because that is exactly what it is — the only unusual thing about it is the timing.
| Known cost | Annual | Monthly set-aside |
|---|---|---|
| Car + health insurance | ₹32,000 | ₹2,667 |
| Festival season | ₹25,000 | ₹2,083 |
| School fees | ₹40,000 | ₹3,333 |
| Annual subscriptions | ₹12,000 | ₹1,000 |
Keep it separate from the emergency fund
They do different jobs. The emergency fund covers things you did not see coming; the sinking fund covers things you did. Mixing them means the emergency fund is quietly spent on Diwali, and is not there in the month it is needed. A separate account, or at minimum a separate tracked goal, keeps the boundary real.
Do you need one
If any month of the last year ended on a credit card because of a bill you knew about in advance, yes. If your irregular costs are genuinely small and your emergency fund is full, the mechanism is optional — but the list is still worth writing, because people consistently underestimate the annual total until they add it up.
Put numbers to it with the free budget calculator and emergency fund calculator — no sign-up, works on any phone.
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