A sinking fund is money you set aside gradually for predictable annual or irregular costs, such as insurance, car expenses, school costs or property charges. Add up what these bills have cost, or are expected to cost, over a year and divide the total by the number of months until they are due, allowing for possible changes. Keeping each purpose in a separate savings pot or account can make the money easier to track, while an automatic transfer may help you build it consistently. Review the amounts when bills change, and keep an emergency fund separate for unexpected expenses.