  title xvi section 1256 contracts  sec 1601 certain swaps, etc, not treated as section 1256 contracts  a in general subsection b of section 1256 of the internal revenue code of 1986 is amended  1 by redesignating paragraphs 1 through 5 as subparagraphs a through e , respectively, and by indenting such subparagraphs as so redesignated accordingly,   2 by striking for purposes of and inserting the following  1 in general for purposes of   , and   3 by striking the last sentence and inserting the following new paragraph  2 exceptions the term section 1256 contract shall not include  a any securities futures contract or option on such a contract unless such contract or option is a dealer securities futures contract, or   b any interest rate swap, currency swap, basis swap, interest rate cap, interest rate floor, commodity swap, equity swap, equity index swap, credit default swap, or similar agreement       b effective date the amendments made by this section shall apply to taxable years beginning after the date of the enactment of this act    