Your Mutual Fund's New Expense Ratio has a Maths Problem

This article is an expanded version of a piece originally published in Mint.

Sometime in May, when April’s mutual fund expense data reaches fact-sheets, screeners, and comparison tools, some funds will appear dramatically more expensive than they were in March. In the first seven days under the new format, over twenty open-ended equity schemes across fourteen categories—including index funds, large-caps, and ELSS—reported a daily TER above 10%. A handful crossed 20%. One thematic fund briefly showed a daily TER above 50%.

Before anyone concludes that AMCs have lost the plot, it’s worth understanding what actually changed and where the new framework’s maths breaks down.

Three Decades of One Number

India’s mutual fund expense structure goes back to 1996. SEBI set TER caps in slabs: 2.5% for the first Rs. 100 crore, stepping down from there. Those slabs stayed untouched for 22 years.

In 2012, SEBI introduced “fungibility.” AMCs could allocate costs however they liked (management fees, distribution, operations) as long as the total stayed within the TER cap. Flexibility for the AMC, but opacity for the investor. You saw one number and had no way of knowing what you were paying for.

The 2018 reforms tightened the slabs and lowered brokerage limits. But the structure stayed the same: one bundled number, one cap. And certain costs—brokerage, STT, stamp duty, exchange charges—always sat outside the disclosed TER. Real costs borne by the fund, invisible to the investor.

What Changed on April 1

The new framework unbundles everything. The disclosed TER is now a formula:

TER = Base Expense Ratio + Brokerage + Transaction Costs + Statutory Levies

The Base Expense Ratio (BER) covers what the AMC controls: management fees, distribution commissions, RTA charges, custodian fees, trustee expenses. It’s the closest successor to the old TER. It is not a clean match since caps and line items have been restructured, but is similar in spirit.

Everything else—brokerage, STT, GST on brokerage, stamp duty, exchange charges—now sits outside the BER but is reported as part of the TER. These costs were always real. Investors just couldn’t see them separately before.

To be clear: nothing has changed from an NAV standpoint. Brokerage, STT, stamp duty, and exchange charges were always deducted from the fund before arriving at the NAV. Investors were always paying these costs. The reform changes the label, not the price.

For context: in the US, the expense ratio explicitly excludes brokerage and transaction costs. India has gone further by pulling them into the headline number. That’s a more aggressive transparency standard, and on principle it’s the right call.

The problem isn’t what SEBI chose to include. It’s how the number gets reported.

You Can’t Annualise a Daily Cost

Each of these components is reported daily and annualised. For BER, annualization makes sense. It’s a relatively stable charge that accrues at roughly the same rate every day. But brokerage, STT, and exchange charges are transaction costs. They hit only on days the fund trades, and they scale with trading volume, not AUM.

Annualizing a single day’s transaction cost assumes that exact level of activity repeats every day for 365 days. That’s not how funds work. An arbitrage fund rolls its derivatives book on specific days. An index fund rebalances when the index changes. An active fund trades when it sees opportunity, not on a schedule.

And then, funds receive inflows and they buy to deploy the money they’ve received. If a fund receives 10% of its AUM as an inflow and buys to just deploy that money, the effective transaction cost is about 0.0172% of the fund value assuming brokerage, taxes and STT. That, when annualized, is a whopping 6.3%! Moreover, that assumes the fund is getting 10% of its AUM every day for the rest of the year, which is extremely unlikely.

The result is a TER number that’s mathematically correct and practically useless.

I pulled AMFI’s first few days of data under the new format. One arbitrage fund reported a TER of 14% on April 1—likely a derivatives-heavy day—then 4.74% on April 2, then dropped to 0.93% on April 3 (a market holiday—zero brokerage, but GST on management fees still accrues daily). The BER was 0.79% on all three days. The TER on an index fund swung from 15.34% on April 1 to 1.47% on April 2 to 1.06% on April 3. The BER: a steady 0.90%.

The daily TER is an indicative, annualised number built on a volatile base. It doesn’t tell investors what they’re actually paying over any meaningful time horizon.

So What Should Investors Actually Do With This

The BER is the number to compare across funds. It is stable, it reflects the AMC’s cost structure, and is what investors can evaluate when choosing a scheme. If you’re picking between two large-cap funds, compare their BERs. That’s the successor to the old TER comparison.

The variable component (TER minus BER) is useful for a different reason: it’s a window into how the fund actually operates.

Before this reform, if you wanted to know how much a fund traded, you’d wait for portfolio turnover ratios reported with a lag. Now you can see it in near-real-time. A spike in an index fund’s variable costs probably means a rebalancing event. Persistent high variable costs in an active fund might signal churn or it might reflect a concentrated deployment phase after large inflows. Either way, you’re seeing something that was hidden before.

Over time, as monthly and quarterly averages stabilise, the variable component will become a reasonable proxy for a fund’s trading intensity. That tells you something about fund philosophy. A value fund with consistently low variable costs is doing what it says: buying and holding. An active fund running several multiples of that is trading far more—and it’s worth asking whether the extra activity is generating returns or just costs.

The daily number, though? Ignore it for comparison purposes. Wait for rolling averages.

What’s Still Invisible

The new framework is a step forward, but transparency has limits worth noting. Exit loads, for instance, don’t show up in the TER. And in India, exit load proceeds are retained by the fund as income (unlike in many other markets where they’re passed to the AMC). That’s money paid by exiting investors and received by remaining investors, and there’s no daily disclosure of it. STT on redemptions—paid by the investor at the point of exit—also sits outside the framework.

Neither of these costs is captured by the new TER. An investor looking at the headline number still isn’t seeing the full picture of what it costs to invest in (and exit from) a fund. SEBI has fixed the biggest gap. A few smaller ones remain.

The Bottom Line

For investors and advisors: focus on BER for fund selection. Treat the daily TER as what it is: a noisy, annualised snapshot of that day’s activity. Watch rolling variable costs for signals about trading behaviour. And don’t compare a fund’s March TER with its April TER. They’re different metrics wearing the same name.

SEBI got the transparency right. The annualisation methodology needs a rethink.