New Delhi, Sept. 6 -- Retiring early is only half the financial challenge. The bigger question is how to make your retirement corpus last for the next 40 years or more without being forced to sell equity investments when markets are falling.

For someone retiring in their 40s or early 50s, conventional retirement rules may not be enough. The popular 4% withdrawal rule, for instance, was developed using US market data and around a 30-year retirement period. An early retiree in India could need to fund a significantly longer retirement while also dealing with inflation, taxes and rising healthcare costs.

"The 4% rule comes from William Bengen's 1994 work on US market data, calibrated to a 30-year retirement on a balanced US stock and bond ...