Not sure what you mean by that so I'll provide some details. Some institutional accounts get paid on credit balances in a type 2 margin account and all market makers do. Many retail accounts do not get paid on type 2 credit balances and if they do it is nominal. Where a retail client can benefit is if they are borrowing based on a high debit balance in a PMA that they can offset with a credit box. E.G. PMA with $500,000 in equity and a debit balance in the type 2 account of $1mm. (Borrowing $500K) If they can sell a box in SPX for more than $500K, it will reduce the debit to not borrowing. If the cost of the box including fees is less than the interest charges, and it does not cause a margin call, it will save money. A type 2 margin account contains cash from a margin account, long stock plus long and short calls. It does not contain short stock.