First, your own contributions are limited to 7/12 of $8,100 = $4,725, not $4,750.
The amount that TurboTax displays as the maximum contribution for each spouse is calculated without regard to the other spouse's contributions and represents the individual limit, not the combined limit. After factoring in the combined contribution limit TurboTax determines your wife's contribution limit to be the correct amount 5/12 of $3,550 (=$1,479.17) plus $1,000 = $2,479.17, not 2,654.17. The $175 error is somewhere in your own calculation of your wife's contribution limit. (I'm guessing that you calculated 5/12 of $3,970 instead of 5/12 of $3,550, then added the $1,000.)
