What one percentage point of fees costs over twenty years

How a fund’s expense ratio is charged, what one percentage point costs across a twenty-year SIP, and why the fee is the only input you can actually control.

The short answer: A fund's expense ratio is charged as an annual percentage of the money you hold, deducted daily from the net asset value rather than billed, which is why it is invisible and why it is underestimated. The effect compounds against you exactly as returns compound for you: on a long SIP, a difference of one percentage point in annual charges typically removes a mid-teens percentage of the final corpus. The reason it deserves attention out of proportion to its size is that it is the only input in the whole projection you actually control — you cannot choose your return, but you can choose what you pay for the attempt.

Key points

The charge is deducted from NAV daily, never invoiced, which is why it costs more attention than it receives.
One percentage point over a twenty-year horizon typically removes a mid-teens share of the final corpus.
Fees are the only variable in a projection you control; the return is an assumption and the horizon is a fact.
A lower fee is not automatically better — compare like with like, because a different mandate is a different product.

What the number means

An expense ratio is the annual cost of running a fund, expressed as a percentage of the assets in it, covering management, administration and distribution. It is charged against the fund's assets rather than billed to you, and accrued daily.

What a fee costs a lump sum over n years: Ending value = P × (1 + r − f)^n versus P × (1 + r)^n

P — the amount invested.
r — the gross annual return before charges.
f — the annual expense ratio.
n — the number of years held.
The gap between the two widens with n, because the fee is deducted from a balance that would otherwise have compounded.

That last line is the whole point and the part that is counter-intuitive. The fee does not merely cost you the fee — it costs you every rupee that fee would have earned for the rest of the horizon, which is why a small annual number becomes a large terminal one.

What one percentage point costs

A twenty-year horizon at an assumed 11% gross

Amount invested: ₹10,00,000 lump sum
Horizon: 20 years
Gross return assumed: 11% a year
At 0.5% expense ratio: ₹10,00,000 × 1.105^20 ≈ ₹72.6 lakh
At 1.5% expense ratio: ₹10,00,000 × 1.095^20 ≈ ₹60.5 lakh
Difference: ≈ ₹12.1 lakh, or about 17% of the higher figure

One percentage point of annual fee removed roughly a sixth of the outcome. Both figures are illustrative — the 11% is an assumption, not a forecast — but the ratio between them depends only on the fee difference and the horizon, and that part is arithmetic.

What to actually do with this

Compare within a category, never across. Two funds with the same mandate can be compared on fee. A cheaper fund with a different mandate is not a cheaper version of the same thing.
Check the direct option. Where a fund offers direct and regular plans, the difference between them is distribution cost and nothing else. Whether that cost buys you advice you value is a real question; whether it changes the underlying portfolio is not.
Weight it by horizon. For a two-year goal the fee is a rounding error. For a twenty-five-year one it is among the largest controllable variables in the whole plan.
Do not chase the last few basis points. Below a point, the difference is smaller than the variation in tracking or in your own contribution consistency, and optimising it is displacement activity.

The broader discipline is to be sceptical of every number in a projection and to know which ones are assumptions. The return is an assumption. The fee is a fact stated in the scheme document — and the SIP formula shows exactly where in the arithmetic it lands.

Reverse Goal Planner: The Reverse Goal Planner solves for the instalment a target requires at a given assumed return — running it at two rates a percentage point apart shows the same effect from the contribution side.

Frequently asked questions

How is an expense ratio actually charged?

It is accrued daily against the fund's assets and reflected in the net asset value, so you never see a deduction on a statement. The return you observe is already net of it. That invisibility is the whole reason a fee that would be scrutinised if invoiced annually goes unexamined for years when it is embedded.

Is a cheaper fund always the better choice?

Only when the two funds are genuinely doing the same job. Comparing an index fund with an actively managed fund on fee alone ignores that they have different mandates and different expected behaviour. Within a category, where the mandate is comparable, the fee is one of the few differences that is knowable in advance rather than hoped for.

Does the fee matter for a short horizon?

Much less. One percentage point over two years is roughly two per cent of the balance — real, but small next to the variation in return over the same period. The fee dominates precisely where the return assumption is most uncertain, which is over decades, because the fee is the part of the calculation that is certain.