If you have a defined benefit (DB) pension, the more years you have in the plan—known as credited service—the higher your pension or the earlier you can retire. It’s why one reader, a Toronto daycare worker, forked out $45,000 to buy back time she’d taken off 20 years ago when she had children. The lump sum buy-back allows her to retire at 55, rather than 60, with a full pension. The incentive: you’ll get guaranteed income in retirement, usually at a better return. But she could have avoided such a large payment. If she’d purchased her missing service time right after taking maternity leave it would have cost her only $4,000. “The earlier you buy back the cheaper it is,” explains pension consultant Brian FitzGerald. That’s because the longer you wait, the more you need to pay to make up for the money that would have accumulated had you invested at the time of your work absence.