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Bullish2 LegsDefined risk

Put Calendar Spread

Sell a near expiry put and buy a far expiry put at the same strike. Profits from time decay if the index stays near the strike, with a mild bullish lean.

By Team Agora Circle

Written by the Agora Circle editorial team. Educational content, explained for the Indian market. Not investment advice.

Market outlook
Neutral to mildly bullish. You want the index at or just above the strike into the near expiry.
Setup
Sell 1 near expiry put and buy 1 far expiry put at the same strike, for a net debit.
Max profit
Reached near the strike at the near expiry, from the value left in the far put. It has no fixed formula.
Max loss
Limited to the net debit paid, if the index moves far from the strike either way.
Breakeven
Two levels either side of the strike that shift as the far put's value changes.
Implied volatility
Net long vega. Rising implied volatility in the far leg helps the position.
Time decay
Time decay works in your favour, because the near put decays faster than the far put.

Strategy Overview

A put calendar spread sells a near expiry put and buys a far expiry put at the same strike. Both are puts at the same level, so it is not a strong directional bet, but the way it is usually placed gives it a mild bullish lean: it does best when the index holds at or just above the strike, letting the near put you sold decay while the far put you own keeps its value.

Like all calendars, the engine is the difference in time decay. The near put, closer to expiry, loses time value faster than the far put, and that widening gap is where the profit comes from while the index sits near the strike. A large move in either direction pulls the two puts together and shrinks the spread back toward its cost.

Because the two legs expire on different dates, the payoff cannot be drawn as a single expiry line. The most you can lose is the net debit, and the profit is realised around the strike at the near expiry, depending on how much time value and implied volatility remain in the far put at that point.

How to Set It Up

Two puts at the same strike but different expiries, bought net long the further date.

  1. 1Choose the strike near where you expect the index to sit, usually at the money or just below.
  2. 2Sell 1 put in the near expiry to collect fast decaying premium.
  3. 3Buy 1 put at the same strike in a later expiry. The net debit is your maximum loss.

Payoff Diagram and Example

Max Profit

Reached near the strike at the near expiry, from the value left in the far put. It has no fixed formula.

Max Loss

Limited to the net debit paid, if the index moves far from the strike either way.

Breakeven

Two levels either side of the strike that shift as the far put's value changes.

This strategy uses two different expiry dates, so a single expiry payoff diagram would be misleading. The value of the longer dated leg depends on the time and implied volatility still left in it when the nearer leg expires, which a fixed expiry chart cannot show. The example and the sections below describe how the position behaves instead.

Suppose NIFTY is at 25,000 and you expect it to hold around that level over the next week or two. You sell the near expiry 25,000 put for 115 and buy the far expiry 25,000 put for 195. The net debit is 80 points, about Rs 6,000 on a lot of 75, and that is your maximum loss.

If the index is still near 25,000 as the near expiry arrives, the short put you sold expires close to worthless, while the far put you own still holds meaningful time value. You can close the far put for more than the net debit, or sell a fresh near put against it to repeat the cycle.

If instead the index runs away to 25,600 or falls to 24,400 by the near expiry, both puts move roughly together and the spread narrows, leaving you close to the maximum loss of 80 points. The trade needs the index to stay near the strike, not to move.

Entering and Exiting

Enter both legs together as a spread so the net debit is fixed and there is no leg risk between fills.

The natural decision point is the near expiry. There you either close the whole spread to bank the gain, or roll by selling a new near put against the far put you still hold.

Because the position wants stillness, exit if the index breaks decisively away from the strike, since the edge from faster near decay disappears once both legs are far in or out of the money.

Time Decay (Theta)

Time decay is the engine of this trade. The near put sits closer to expiry, so its time value bleeds away faster than the far put's, and that widening gap is the source of profit while the index stays near the strike.

This favourable decay is strongest when the index is right at the strike and both puts are at the money. The further the index drifts, the less the decay advantage matters.

Implied Volatility (Vega)

The position is net long vega, concentrated in the far put, so a rise in implied volatility generally helps. Entering when volatility is low and expected to rise into the far expiry improves the odds.

The risk is a fall in implied volatility, which deflates the far put you own. Calendars entered when IV is high can suffer if volatility drops even while the index behaves, so the level of IV at entry matters as much as the index level.

Common Adjustments

The classic adjustment is rolling: at the near expiry, sell a fresh near put against the far put to collect more premium and lower the position's cost, turning a single calendar into a repeating income structure.

If the index drifts, you can roll the whole calendar to a new strike centred on the new level, keeping the position near the money.

If implied volatility has risen sharply and the far put has gained, closing the spread to bank the volatility gain can be better than waiting for the near expiry.

Synthetic Equivalent

A put calendar spread has no equivalent built from a single expiry; its edge comes entirely from the difference in time decay between two expiries at the same strike.

Its call counterpart, a call calendar at the same strike, has a nearly identical payoff shape, so the two are chosen based on which options price and trade better.

Pros and Cons

Pros

  • Profits from time decay while the index stays near the strike.
  • Maximum loss is limited to the small net debit paid.
  • Net long volatility, so it benefits from a rise in implied volatility.
  • Can be rolled repeatedly to generate income against the far put.
  • Low cost relative to the exposure it creates.

Cons

  • A large move in either direction erodes the position toward its maximum loss.
  • A fall in implied volatility hurts the long far leg even if the index behaves.
  • The payoff is harder to visualise because two expiries are involved.
  • Needs liquid options in two expiries, which can mean wider spreads in the far month.

Frequently Asked Questions

Why can't a put calendar's payoff be shown on one chart?

Because its two legs expire on different dates. When the near put expires, the far put is still alive and its value depends on the time and implied volatility remaining in it, which a fixed expiry chart cannot capture. The profit is assessed at the near expiry, not at a single shared one.

Why is a put calendar seen as mildly bullish?

Because it is usually placed so it does best when the index holds at or just above the strike. The near put you sold then decays fastest, which is a gently bullish preference, even though the structure profits mainly from stillness rather than direction.

How much is actually at risk on a put calendar spread?

The net debit paid, which occurs if the index moves far from the strike so that both puts move together and the spread collapses. In the example that is 80 points, or Rs 6,000 on one lot.

Does a put calendar prefer rising or falling volatility?

The position is net long vega through the far put, so rising implied volatility helps and falling IV hurts. Because of this, the IV level when you enter matters a great deal, and a calendar can lose even when the index cooperates if volatility drops.

How do I roll a put calendar spread?

At the near expiry, you sell a new near put against the far put you still hold. This collects fresh premium and lowers the cost of the position, letting you repeat the decay harvest while you keep the longer dated put.

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This page is for education only. It is not investment advice, and nothing here is a recommendation to buy or sell any instrument. Options involve substantial risk, and option sellers can lose far more than the premium they receive. Please do your own research or consult a SEBI registered investment adviser before trading. Read our full disclaimer.

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