married filing separately - go into forms mode and see what is stated below line 4 on form 8582.
code section 469 in part
(5) Married individuals filing separately
(A) In generalExcept as provided in subparagraph (B), in the case of any married individual filing a separate return, this subsection shall be applied by substituting—
(i) “$12,500” for “$25,000” each place it appears,
(ii) “$50,000” for “$100,000” in paragraph (3)(A), and
(iii) “$100,000” for “$200,000” in paragraph (3)(B).
(B) Taxpayers not living apart
This subsection shall not apply to a taxpayer who—
(i) is a married individual filing a separate return for any taxable year, and
(ii) does not live apart from his spouse at all times during such taxable year.
this means if married filing separately and lived with spouse any time during the year the special allowance is reduced to $0