I am using TT Home and Business desktop and the MFJ vs MFS "what if" is not allocating 1099-DIV and 1099-INT amounts correctly for the "what if".
When I import , for example, my spouse's TD Ameritrade 1099 amounts, TT doesn't ask "who" these amounts are for ( why?). I can go in and manually fix the ownership in the Schedule B worksheet forms but this is NOT reflected in the columns 3 and 4 in the "what if" spreadsheet. TT just allocates the 1099 totals 50% to me and 50% to my spouse making the "what if" useless.