New Delhi, July 29 -- Anita and Sanjay, both in their forties, laughed off the idea that retirement would be expensive. Without children, they assumed they would need far less money than couples with kids and hoped to retire within the next few years.

Many child-free couples make the same assumption: without the cost of raising children, they will need less money in retirement. On paper, the logic seems sound. In reality, retirement planning for child-free couples is often more complex. They face a different set of financial goals, risks and priorities, and, paradoxically, may need a larger retirement corpus.

The biggest risk is underestimating the cost and complexity of ageing. Child-free couples need to confront practical questions ea...