Option Writing (Selling) in Indian Markets

What Option Writing Actually Means

Option writing, also called option selling, is the act of selling a call or put contract that you do not already hold. When you write an option you receive the premium immediately, and in exchange you take on the obligation to settle the contract if the buyer's view comes true. In Indian markets all index options such as Nifty, Bank Nifty, Fin Nifty and Sensex are cash settled, so there is no delivery of shares. On expiry the in the money value is simply debited or credited to your account in rupees.

The writer is on the opposite side of the buyer. A call buyer wants the index to rise, so the call writer profits when the index stays flat or falls and the option loses value. A put buyer wants the index to fall, so the put writer profits when the index stays flat or rises. The single biggest reason traders write options is time decay, the slow erosion of an option's price as expiry approaches. The seller is effectively collecting that decay every day the option does nothing.

The trade off is asymmetric. Your maximum profit is fixed at the premium you collected, but your loss is not. A naked short call has no upper bound on loss because an index can in principle keep rising, and a naked short put loses value all the way down until the strike is worth zero. This is why writing is described as picking up small, steady gains while occasionally facing a large drawdown, and why margin and position sizing matter far more here than for option buyers.

Lot Sizes and Why They Change Everything

You never write a single unit of Nifty. Every contract is a fixed bundle of units called a lot. Profit and loss is always the change in premium multiplied by the lot size and the number of lots, so the lot size silently multiplies every rupee of risk. A premium move of just Rs 10 on one Nifty lot is Rs 750, and on five lots it is Rs 3,750. Knowing the exact lot size is the first step before any position is sized.

SPAN and Exposure Margin: The Real Capital You Need

Unlike buying an option, where you only pay the premium, writing an option requires you to block a large margin upfront. This margin has two parts. The SPAN margin (Standard Portfolio Analysis of Risk) is calculated by the clearing corporation using a worst case move of the underlying, and it forms the bulk of the requirement. On top of that sits the Exposure margin, an additional buffer that the exchange charges to cover gap risk. Your total upfront blocked capital is SPAN plus Exposure.

As a rough illustration, writing one lot of a near the money Nifty weekly option typically blocks around Rs 1.1 lakh to Rs 1.4 lakh, and one lot of Bank Nifty around Rs 1.3 lakh to Rs 1.6 lakh, depending on volatility and how close the strike is to spot. These numbers are not fixed. When implied volatility rises or a result or event is near, SPAN margin can jump 20 to 40 percent in a single day, and a seller who is fully deployed can face a margin shortfall and penalty even without the price moving against them.

• SPAN margin is the exchange's estimate of the worst likely one day loss on your position. It changes through the day as volatility changes.
• Exposure margin is an extra fixed buffer on top of SPAN, charged to cover sudden gaps.
• SEBI's peak margin rules require the full SPAN plus Exposure to be available upfront. Brokers no longer offer intraday margin relief for writing.
• A margin shortfall attracts a penalty from the exchange, so always keep a cushion of free cash above the blocked margin.
• Selling a hedged spread (buying a further out option against your short) sharply reduces margin compared with naked writing, often by 60 to 70 percent.

Worked Example: Writing a Bank Nifty Monthly Call

Suppose Bank Nifty spot is at 48,000 and you write one lot of the 48,500 monthly call, collecting a premium of Rs 180 per unit. The lot size is 30. All figures below are illustrative and not a forecast or a promise of returns.

• Premium collected upfront: Rs 180 times 15 equals Rs 2,700 credited to your account.
• Margin blocked: roughly Rs 1.4 lakh of SPAN plus Exposure for this one short call.
• Best case, expiry below 48,500: the call expires worthless, you keep the full Rs 2,700 before costs. That is your maximum profit, it cannot be more.
• Break even on expiry: 48,500 plus 180 equals 48,680. Above this level you start losing.
• Bad case, Bank Nifty closes at 49,000: the call is worth 500 at expiry. Loss is (500 minus 180) times 15 equals Rs 4,800 before costs.
• Worse case, a sharp rally to 49,800: the call is worth 1,300. Loss is (1,300 minus 180) times 15 equals Rs 16,800 before costs, which is more than six times the premium you collected.

This single example shows the core nature of writing. You risked roughly Rs 1.4 lakh of margin to earn a maximum of Rs 2,700, while a 3.75 percent move against you wiped out six times that premium. Now layer on costs. On the sell leg, STT is 0.15 percent of the premium value, which here is 0.15 percent of (180 times 15) equals about Rs 4.05. Add brokerage (flat, often Rs 20 per order on discount brokers), exchange transaction charges, SEBI fees, stamp duty on the buy side and 18 percent GST on brokerage plus transaction charges. For a one lot trade these costs are small in rupees but they scale up fast across many lots and many trades, and they always reduce a writer's thin edge first.

How Profit and Loss Is Calculated on Any Short Option

The formula is the same for every contract. Profit or loss equals (premium received minus premium now, or settlement value) times lot size times number of lots, minus costs. Because you are short, falling premium is your profit and rising premium is your loss. Most writers never hold to expiry. They buy back the option once a target portion of the premium has decayed, locking in the gain and freeing the margin for the next trade.

Notice the symmetry of the math but the asymmetry of the outcome. The two profit rows are bounded by the Rs 120 you collected, so the best a flat or falling market can give you on this one lot is Rs 9,000. The loss rows have no such cap, and a single sharp move produced a Rs 21,000 loss. This is exactly why disciplined writers define a stop loss in premium terms (for example, exit if the premium doubles) before they ever place the trade.

F&O Turnover and the Tax Audit Threshold

For income tax, F&O turnover is not the contract value or the notional you control. As clarified by the ICAI guidance widely followed for F&O, turnover is the absolute sum of profits and losses on every trade. For options, the premium received on options sold is also added to this absolute turnover. So a year of small wins and losses can add up to a modest turnover figure even though the contracts controlled crores of notional value.

• Turnover equals the sum of absolute profit and absolute loss on each squared off trade.
• For options, the premium on options sold is included in turnover as well.
• This turnover decides whether a tax audit under Section 44AB applies. Broadly, an audit can be required if turnover crosses Rs 10 crore where over 95 percent of receipts and payments are digital (which is the norm for F&O), and the lower Rs 1 crore and Rs 2 crore limits and the 44AD presumptive route can come into play in other cases.
• Because almost all F&O money flows are through the banking and broker system, the higher Rs 10 crore digital limit is what most active writers measure against, but the rules are detailed and change, so confirm your exact case with a chartered accountant.
• Keep your broker's full year P&L statement and tax P&L report, which already compute turnover, charges and STT for you.

How Option Writing Income Is Taxed in India

Income from writing options is treated as non speculative business income under the Income Tax Act. This is a crucial distinction. It is not capital gains, so the STCG rate of 20 percent and the LTCG rate of 12.5 percent above Rs 1.25 lakh that apply to delivery equity do not apply to your F&O writing profits at all. Instead your net F&O profit is added to your other income and taxed at your slab rate, which ranges from nil up to 30 percent plus applicable surcharge and 4 percent cess.

Because it is business income, you can deduct genuine trading expenses against your F&O profit, such as brokerage, STT paid, exchange and SEBI charges, GST on those charges, broker software or data subscriptions, internet, advisory fees and a reasonable share of related costs. A net F&O loss can be set off against other business income and, if it remains, carried forward for up to eight assessment years to offset future business income, provided you file your return by the due date. This makes accurate record keeping and timely filing genuinely valuable for active writers.

These rates reflect the Budget 2024 changes and are stated as illustrative current figures for 2026. Tax law changes, and individual situations differ, so verify the current rates and your audit position with a qualified chartered accountant and the official Income Tax portal before filing.

Weekly Versus Monthly Expiry Mechanics

Index options in India have weekly and monthly expiries, and the choice shapes a writer's risk. Weekly options expire fast, so their time decay is steep and a writer collects premium quickly, but they are also far more sensitive to a sudden move in the last day or two. Monthly options decay more slowly and give more room, but they tie up margin for longer and carry overnight gap risk across many sessions, including earnings, policy and global events.

SEBI moved in 2024 and 2025 to rationalise weekly expiries so that each exchange offers weekly contracts on a single benchmark index, reducing the earlier crowding of daily expiries. The exact expiry day for each index is set by the exchange and has been revised, so always confirm the current expiry calendar on the NSE or BSE website. On expiry day, in the money index options are cash settled against the settlement value, and a writer who has not squared off will see the intrinsic value debited, plus STT on exercised in the money options. Holding a short option into expiry is therefore a deliberate decision, not a default.

• Weekly expiry: fast time decay, lower margin holding period, but sharp last day risk.
• Monthly expiry: slower decay, more breathing room, longer margin lock and more overnight events.
• On expiry, index options are cash settled. There is no share delivery for index contracts.
• Confirm the current expiry day and weekly index list with the exchange, as SEBI rationalised these rules recently.

Naked Writing Versus Hedged Writing

There is a world of difference between writing a naked option and writing inside a hedged structure. A naked short call or put collects the most premium and needs the most margin, and it carries the open ended loss profile shown in the examples above. A hedged position, where you also buy a cheaper, further out option, caps your maximum loss, slashes your margin requirement and turns the trade into a defined risk spread.

For example, instead of naked selling the Bank Nifty 48,500 call, you could sell it and simultaneously buy the 48,900 call. The bought call costs some premium and reduces your net credit, but it puts a ceiling on your loss at the 400 point spread width minus the net credit, multiplied by the lot of 30. Your margin can fall by more than half because the exchange recognises that the long option offsets your risk. Most professional retail writers use such spreads precisely because the capped loss and lighter margin let them survive the occasional sharp move that would otherwise be devastating.

• Naked writing: highest premium, highest margin, open ended loss. Suited only to well capitalised, disciplined traders.
• Credit spread: sell one option, buy a cheaper further out option. Loss is capped, margin is far lower, premium is smaller.
• Iron condor and similar structures combine a call spread and a put spread to profit from a range bound market with defined risk.
• Always know your maximum loss in rupees before you place the trade, computed as spread width times lot size minus net credit received.

Risk Management Rules for Writers

Because the loss side is open ended, survival depends on rules, not on being right often. Most successful writers cap how much margin any single position uses, predefine a premium based stop loss, and refuse to add to a losing position. A common discipline is to exit when the premium of a short option roughly doubles, which keeps any single loss to about the premium collected and prevents the rare large move from compounding into account ending damage.

Event awareness is equally important. Margins rise and gaps are larger around the monetary policy, the union budget, major results and global shocks, so many writers reduce size or stay hedged through such windows. Keeping a trading journal of every written position, the premium, the margin used, the exit reason and the realised P&L turns writing from a hopeful habit into a measurable process you can actually improve. Use risk management as the core of the strategy, not as an afterthought.

Sources and Further Reading

For authoritative data and current contract specifications, expiry calendars, lot sizes, margin and STT rates, refer to NSE India, SEBI and the Income Tax Department. All numbers here are illustrative for 2026 and not a forecast or a promise of returns. Always confirm current rules, rates and contract details on the official source, and consult a qualified chartered accountant for your tax position, before you trade.

Sources and Further Reading

For authoritative data and further reading on this topic, refer to NSE India, SEBI (Securities and Exchange Board of India) and Income Tax Department. Always confirm current rules, rates and contract specifications on the official source before you trade.