I've been using MTM accounting for a long time to good advantage for my trading account . I've used your link for some great info, too.
Interactive Brokers is now my only MTM account. They have shockingly exquisitely detailed trade information reporting for MTM, but despite extensive efforts I've been unable to use their Flex report-building capabilities to build the Schedule D format the IRS requires (even for MTM).
[i.e.,
(a) Desc of Property
(b) Date acq
(c) Date sold
(d) Gross sales price
(e) Cost or other basis
(h) GAIN or (LOSS)]

Has anyone worked out an IB Flex algorithm for IRS-compliant MTM tax reporting? I know it's possible (& probably pretty easy) but I'm just not skilled/knowledgable enough. I spend a lot of time every year Excel-hand-modifying the IB 1099. I'm pretty sure a lot of IB MTM traders would like to know this - if they don't already. ;-)
Thanks in advance, & apologies in advance for the drill-down specificity of the request.
:-)Shawn