How to Properly Report Box Spread Loans for Tax Purposes

The Section 1256 reporting detail most investors (and CPAs) miss

Box spreads use options to synthetically borrow against a portfolio at a low, fixed rate. (currently below ~4% in many cases)

The financing cost shows up as an unrealized loss on the options positions. Because box spreads typically use Section 1256 contracts, all open positions are marked to market on 12/31, whether you close them or not.

Section 1256 gai…