Sizing a retirement corpus a client can trust
A practical framework for sizing a retirement corpus from income, inflation and longevity, then finding the monthly amount that closes the gap.
The short version
Sizing a retirement corpus comes down to four honest questions. What income will the client want in their first year of retirement, in tomorrow's rupees. How long must that income last. How much of it can their existing savings and retirement balances already cover. And what monthly amount closes the rest before they stop earning. Get these four right and the number you hand over will survive scrutiny. Guess at any one of them and the number looks neat on paper but breaks the first time inflation or a long life tests it. This guide walks through each step the way you would actually do it in a client meeting, with illustrative rupee figures so the method is concrete.
Start from desired income, not a round-number corpus
Clients love to ask for a target like 'I want 5 crore'. That number means nothing on its own. Anchor instead on the income they want to draw in their first year of retirement, expressed in today's money. A useful starting point is a replacement ratio. Many retirees need roughly 70 to 80 percent of their pre-retirement spending, because work-related costs, EMIs and the SIPs themselves usually fall away, while some categories rise. Work from current spending, not current income, since income includes savings the client will no longer make. The cleanest way to get this number is to sit with the client and build a simple monthly budget for the life they actually want, then test it against what they spend now.
Inflate that income to the retirement date
The income figure is in today's rupees, but retirement may be twenty or thirty years away, so it has to be inflated to the retirement date. Use a general inflation assumption of around 6 percent for living costs, and treat healthcare separately at a higher rate, often 8 to 10 percent, because medical inflation in India runs well above the headline number. Here is why this matters. A client spending 60,000 a month today, or 7.2 lakh a year, needs that grossed up at 6 percent over 25 years. The multiplier is roughly 4.3, so the same lifestyle costs about 31 lakh a year on the day they retire. Size a corpus against today's 7.2 lakh and the client is under-funded by a factor of four. Always show the client the inflated first-year number. It is the single most persuasive figure in the whole conversation.
Account for a long life, and inflation that keeps running
Retirement does not end on the retirement date, and neither does inflation. A 60-year-old Indian client today can reasonably expect to live to 85 or 90, and for a couple the money has to last until the second person, not the first. So the corpus must fund 25 to 30 years of withdrawals that themselves rise with inflation every year. There are two common ways to size this. The simpler rule of thumb multiplies the inflated first-year income by 25 to 30. Against our 31 lakh first-year figure, a 25x multiple points to a corpus near 7.75 crore, and 30x to about 9.3 crore. The more rigorous method runs a year-by-year drawdown: each year the corpus earns an assumed post-retirement return of say 8 percent, the client withdraws a sum that grows 6 percent annually, and you check that the balance lasts to age 90 without hitting zero. The drawdown view is better because it captures the real risk, which is that early withdrawals plus inflation drain the corpus faster than returns refill it.
The safe-withdrawal lens, adjusted for India
The famous 4 percent withdrawal rule comes from US data and does not transfer cleanly to Indian conditions, where inflation has historically been higher. Treat it as a sanity check, not gospel. A more conservative 3 to 3.5 percent initial withdrawal rate is a sensible Indian starting point for a 30-year horizon, with the rupee amount rising each year for inflation. Flip the arithmetic to size the corpus: divide the inflated first-year income by the withdrawal rate. At a 3.5 percent rate, our 31 lakh income implies a corpus of about 8.85 crore, which sits neatly between the 25x and 30x rules of thumb. Two practical cautions. First, sequence-of-returns risk is real: a poor market in the first three or four years of retirement does far more damage than the same fall later, and it is the risk a cushion of a few years' spending, kept apart from money that can fall in value, is meant to soften. Second, withdrawal rates are not set once and forgotten; revisit them every year or two as markets and the client's health change.
Credit what the client already has
The gross corpus is only half the calculation. Now subtract what is already working toward retirement, grown to the retirement date: investments already held, provident fund and pension balances with the contributions still to come, and any other savings set aside for it. Two cautions. Some pension balances cannot all be taken as a lump sum at retirement, so credit only the part that can be drawn freely. And any pension or rental income is better netted off the income need than added to the corpus. The discipline is to convert every existing asset into its value on the retirement date, not its value today, so you are comparing like with like.
Find the gap, then turn it into a monthly amount
Subtract the projected value of existing savings and retirement balances from the gross corpus target. What remains is the gap that new saving has to fill. Suppose the target is 8.85 crore and the client's existing savings come to 3.85 crore at retirement; the gap is 5 crore. Now solve for the monthly SIP that grows into 5 crore over the working years using a standard future-value calculation for a monthly series. As an illustration, reaching 5 crore in 25 years at an assumed 11 percent annual return needs roughly 35,000 to 37,000 a month. Two adjustments make this realistic rather than discouraging. A step-up that rises perhaps 8 to 10 percent a year in line with the client's income can cut the starting amount substantially and matches how salaries actually grow. And the number should be tested again every year, because a missed year or a market swing changes the required contribution. The FinClarus report does this arithmetic for retirement: it sizes the corpus from the monthly expense entered, grows the retirement savings entered to the retirement date, shows the gap, and works out the monthly amount that closes it, with a starting amount that rises 10 percent a year where today's surplus falls short, so the client sees the path on one page instead of in a spreadsheet.
Pressure-test the number before you present it
A number the client can trust is one that survives a few hard questions, so ask them yourself before the meeting. What if returns are two percentage points lower than assumed, or inflation two points higher. What if the client retires three years early, or lives to 95. What if a medical event front-loads spending. Run the corpus against these and you will usually find it needs a buffer of 10 to 20 percent above the base figure, which is more honest than presenting a single point estimate as certainty. Common pitfalls to catch: ignoring medical inflation, sizing for the first death in a couple rather than the second, forgetting that part of some pension balances cannot be drawn as a lump sum, assuming working-years returns simply continue after retirement, and quoting the corpus in today's rupees so it looks smaller and more achievable than it truly is. Close the conversation by showing the client three things: the inflated first-year income, the corpus gap, and the monthly amount that bridges it. When those three numbers hang together, the client believes them, and a number the client believes is one they actually fund.
This guide is general information for advisers, not investment advice. Every client report is an estimate the adviser reviews and is responsible for.