A freelance designer earns between Rs 40,000 and Rs 1.2 lakh a month, with average expenses of Rs 45,000. Design his emergency buffer and investing rule so that a bad month never forces him to sell equity.

Build a six-month buffer of Rs 2.7 lakh, pay himself a fixed Rs 45,000 from it, run a small Rs 10,000 SIP, and invest only what overflows the buffer. On last year's income the buffer never fell below Rs 2,51,000 and swept Rs 1,14,000 into equity on top of the SIP. Even three Rs 40,000 months plus a Rs 50,000 surprise draw only about Rs 1,07,000 from it, so equity is never sold for a bill.

Because a salaried rule assumes the same money arrives every month. A farmer does not spend the harvest the week it comes in; he stores grain to eat through the lean months. For a freelancer, the buffer is the granary: it turns lumpy income into a steady salary, and only once the granary is full does anything go to investments. A standard SIP set at his average income of about Rs 71,667 would have to be paused, or funded by selling, in the four months last year his income was Rs 45,000 or less.

Size it to the expense, not the income. Six months of Rs 45,000 is Rs 2.7 lakh, the amount he already has; freelancers with fewer clients or longer gaps between projects might hold nine. Keep it where it can be reached in a day without a loss: about a month's costs in the savings account and the rest in a liquid or overnight fund, which pays more than a savings account and can be redeemed quickly, though it is not a bank deposit and carries a small risk. The 10% tax pot sits separately so an advance tax instalment never looks like spare money.

Three parts. Every month, pay himself Rs 45,000 from the holding account and send Rs 10,000 to the SIP, whatever came in. At month end, anything above the Rs 2.7 lakh target is swept into an equity top-up. In a slow month the buffer pays the shortfall; in a good month it refills before anything is invested. Run on last year's income, the buffer's lowest point was Rs 2,51,000, and the year sent Rs 2,34,000 to equity: Rs 1.2 lakh through the SIP and Rs 1,14,000 in top-ups.

Stress it beyond last year. Three Rs 40,000 months in a row leave a shortfall of Rs 19k each month, and add a Rs 50,000 surprise, a laptop or a hospital bill: the buffer gives up about Rs 1,07,000 and still holds over Rs 1.5 lakh. The SIP could keep running even then. The limit: a long drought, six months without work, would empty the buffer, and the rule then is to pause the SIP before touching equity. The view to close on: the buffer is not idle money; it is what lets the rest of his money stay invested through bad months.