Guide · Derivatives · Stage 2 · Keyword: F&O lot size revision

F&O lot size revisions: what they do to your positions, and how to find the current lot

The news framing of a lot-size revision is a single number changing, and most write-ups stop there. For a trader who is actually holding or rolling positions through the change, the number is the least of it. What matters is that the change lands unevenly across expiries, that it moves your per-lot notional and margin only on the contracts you open next, and that it quietly shifts your tax turnover. This is the practical, position-facing guide. For the regulatory reason lots are revised at all, the contract-value band that drives it, and the full chronology, read the companion piece: why SEBI revises F&O lot sizes. Here we take the mechanism as given and work out what it does to you.

The one thing most pages miss: a revision does not resize what you already hold

Start with the mechanic that saves the most money because it is the one most sources skip. A lot-size revision does not reach back and change contracts that already exist. Every series that was listed before the effective date keeps its original lot size, its original quantity per lot, and its original margin, all the way to its own expiry. The revised lot attaches only to series that the exchange introduces on or after the effective date.

That single rule has an immediate consequence that surprises people. During the changeover window, the running near-month, listed under the old specification, still trades on the old lot until it expires. Meanwhile a farther-dated series, freshly listed under the new specification, is already trading on the new lot. For that window, one underlying carries both lot sizes at the same time, split across expiries. Nothing is wrong; this is exactly how the transition is designed, and the exchange spells it out in the revision circular.

What actually happens to your position, case by case

Reduce the mechanic to the four situations a trader is actually in when a circular lands. The pattern is consistent: anything already open is safe on the old lot, and anything you open next inherits the new one.

The rollover row is where real money goes astray. A roll is a close of the near expiry and an open of a farther one. If the near leg is an old-lot series and the far leg is a new-lot series, rolling one lot into one lot no longer preserves your quantity, and quantity is what your exposure and margin are actually built on. A trader who rolls by habit, one lot out and one lot in, can end the roll holding a position materially larger or smaller than intended. The discipline is simple: before any roll across a revision, read the destination series lot in the contract file and match the roll by quantity.

The margin and notional impact, before and after

The lot is the multiplier that turns a price into money. One lot of an index or single-stock derivative is worth the lot size times the underlying price, and the margin the exchange demands, the SPAN plus exposure requirement, scales with that rupee notional. So the moment a revision changes the lot on the series you trade next, it changes both the value of one lot and the capital to carry it. This bites hardest when a revision raises the contract value, or when SEBI lifts the minimum contract-value band, because then one new lot is a bigger commitment than one old lot was.

Two practical points follow. First, only the new-lot series is affected: your existing old-lot position keeps its old margin until it expires, so do not expect a margin call on it from the revision alone. Second, size in quantity, not lots. If your risk rule allowed a certain exposure at the old contract value, the same lot count is a different exposure now, so recompute how many new lots your risk budget permits against the new notional, and confirm one lot still fits the account. The lot revision does not change your risk appetite; it changes the granularity you can express it in.

How to find the current lot for any contract

This is the evergreen half of the question, and the honest answer is that a lot size is not something to memorise or to trust from an article. The exchange sets each lot so the contract value sits inside a defined band, and it revises the lot from time to time to keep it there, so the number is a moving target by design. The authoritative source is always the exchange itself, in one of three places.

The workflow is short. To confirm a live lot, read the contract specification page or the daily contract file. To understand a change that is coming, read the market-lot circular, which is the only source that also tells you the effective date and how existing series transition. Any lot quoted in an article, including this one, is a snapshot that can be superseded at the next review, so use it to learn the mechanism and confirm the live figure at the source before you trade or size.

The tax-turnover interaction most traders never connect

Here is a second-order effect that sits well outside the news framing. For income-tax purposes, F&O turnover is not the notional value you traded. It is the absolute sum of your profits and losses, adding the size of each gain and each loss regardless of sign. That definition is what makes a lot revision touch your tax position at all.

The link is direct. A larger lot makes each point of price movement a larger rupee amount, so the profit or loss booked on one lot grows in proportion. Because turnover is built from the absolute size of those per-trade results, a larger lot inflates the turnover figure for the same trading behaviour. Trade the identical view in the identical number of lots after an upward revision, and the turnover you report can be higher, purely because each lot now moves more money. Since the tax-audit thresholds are defined against turnover, that shift can matter at the margin of an audit trigger. The full mechanics of the turnover definition and the thresholds are in the dedicated guide to F&O taxation in India; the point to carry here is only that a lot revision is quietly a turnover event, not merely a sizing one.

The recent revisions, in one paragraph

To place this in time without re-deriving it: under a SEBI framework announced on 1 October 2024, the minimum contract value for index derivatives was raised to a band of roughly 15 lakh to 20 lakh rupees, up from the earlier 5 lakh to 10 lakh region. Exchanges lifted index lot sizes for new series from 20 November 2024, with existing weekly and monthly series running to expiry on their old lots and longer-dated series transitioning in late December 2024, an event that showed the mid-life mechanic in full public view. The band is then reset periodically as index levels drift, including a further index-lot revision effective from the January 2026 series, where index lots were adjusted downward to keep the contract value inside the band as levels had risen. Those specific figures are as of their dates and should be confirmed live. The full rationale, the band arithmetic, and the chronology are the subject of the companion article on why SEBI revises F&O lot sizes; the lot size as an idea, rather than a number, is covered in what a lot size is in F&O.

Where this sits, and what to actually do

A lot-size revision is a routine, forward-looking adjustment, not a shock to the book you already hold. Reading it correctly is three habits. Recognise that your open series are untouched and only new series carry the change. Size and roll in quantity, not in lot count, whenever a revision straddles your positions, so a rollover or a spread does not silently change your exposure. And treat the lot as a number you verify at the exchange, not one you memorise, because it is built to move. That upstream discipline, sizing from risk and reading the specification before acting, is exactly what the method we teach is built around; the revision is just an occasion that rewards it.

Frequently asked questions

Sources

Where the facts come from

• SEBI index-derivatives framework, 1 October 2024. Raised the minimum contract value for index derivatives to a band of about 15 lakh to 20 lakh rupees at review, the change that drove the November 2024 upward lot revision. sebi.gov.in
• Exchange market-lot revision circulars. The National Stock Exchange publishes periodic circulars revising the market lot of derivative contracts, stating the old and new lot, the effective date, and that existing series continue on their original lot to expiry while new series carry the revised lot. nseindia.com
• Contract specification and daily contract file. The exchange contract specification pages and the daily contract master file (the NSE_FO_contract file) carry the live market lot per underlying, and are the authoritative place to confirm a current lot. nseindia.com
• F&O turnover definition. For income-tax purposes, F&O turnover is computed as the absolute sum of profits and losses, not the notional value traded, which is why a lot revision changes the turnover figure. See the dedicated F&O taxation guide for the thresholds.