That is an interesting question. The broker charges you SPAN + ELM margins, which is mandatory as per SEBI regulations. Typically, if you are long on stock futures, then your broker will start collecting 40% of the value on Monday and progressively take it closer to 100% by expiry day. But what happens on Monday if you’re SPAN + ELM is already 65%, as is possible in case of many stocks? In such cases, the higher of the two will be collected by the broker. The brokers have the discretion to decide on this waterfall based on their risk perception.