Retirement Goal Monthly Contribution

Retirement target with compound interest

When you build toward a target through monthly contributions that earn compound interest, the future value is FV = PMT × ((1+i)^n − 1) / i. Here i is the monthly real rate and n the number of months. Flip the equation around and you get the monthly contribution you actually need. There's also the well-known 25× rule from the Trinity Study (1998): hold a portfolio worth 25× your annual spending and you can pull a 4% safe withdrawal rate, adjusted for inflation, for at least 30 years under historical 60/40 equity/bond allocations. Take R$ 1 million in 30 years at 6% real per year. That works out to about R$ 996/month, which is manageable if you start early and punishing if you wait. One rule never bends here: use the real rate (above inflation), never the nominal Selic.

Applications

People use it to plan FIRE (Financial Independence, Retire Early), to size income that tops up the INSS, and to weigh PGBL (deductible up to 12% of taxable income, taxed on withdrawal) against VGBL (no deduction, taxed only on gains). It also tells you whether your current contributions will land on the target by the deadline.

FAQ

What real rate is reasonable? Over the long haul, Brazilian portfolios have delivered 4%–7% above inflation. A sensible base case is 5%–6%, and it's worth checking how the plan holds up at 3%.

Does INSS replace this? Only up to a point. The INSS ceiling sits around R$ 8,150 (2026), and whatever you spend beyond that has to come from private capital.

What's the 4% rule's blind spot? Sequence-of-returns risk. If the market crashes in the first 5 years of retirement, the portfolio takes a hit it may never recover from. For long horizons, some planners drop the rate to 3%–3.5%.

PGBL or VGBL? Go with PGBL if you file the full IRPF return and want the up-to-12% deduction; otherwise VGBL. Either way the money compounds tax-deferred, and you choose between regressive taxation (10% after 10 years) or progressive.