A calendar put spread that is established by selling a front-month put option at a given strike price and buying a back-month put option at the same strike price. This spread is mainly created to benefit from the expectation that the underlying will remain stagnant at the time when the front-month option expires. To that end, it plays on accelerated time decay on the shorter-term put as it approaches expiration. If an investor is expecting limited movement in the underlying, the position is better constructed using at-the-money puts. For moderately bearish investors, slightly out-of-the-money puts are better be used to create the spread.

The maximum potential profit from this strategy is limited to the premium received for the longer-term put minus the premium paid to buy the shorter-term put, net of the initial cost (the net debit amount) paid to create this position.

The long calendar put spread is an alternate name for a long put calendar spread.