Typically about 3%-5% of value of underlying contract

Margin is deposited when a contract is either bought or sold. Margin is returned when position is closed. Margin amount is adjusted daily.

Two types of margins:

Standard margin - initial margin deposited

Variation margin - change in margin when marked to market

SPAN (Standard Portfolio Analysis of Risk) margin delivered by exchange to broker daily which the brokers use to input into their systems and charge margin to clients.