TurboTax does not support Form 8621. You would have to fill it out by hand and and mail in the return. Line 5 has c) Section 1296 (Mark to Market)
Any amount included in gross income under subsection (a)(1), and any gain on the sale or other disposition of marketable stock in a passive foreign investment company (with respect to which an election under this section is in effect), shall be treated as ordinary income.
(B) Loss Any—
(i) amount allowed as a deduction under subsection (a)(2), and
(ii) loss on the sale or other disposition of marketable stock in a passive foreign investment company (with respect to which an election under this section is in effect) to the extent that the amount of such loss does not exceed the unreversed inclusions with respect to such stock,
shall be treated as an ordinary loss. The amount so treated shall be treated as a deduction allowable in computing adjusted gross income.
<a rel="nofollow" target="_blank" href="
https://www.law.cornell.edu/uscode/text/26/1296">https://www.law.cornell.edu/uscode/text/26/1296</a>
