Federal Income tax calculations can be weird, especially if using the tax table tables. The tables take your total pay multiplied by the number of times in a year your will be paid and calculate the tax on that based on the sliding scale.

The total payment is basically 30K. This get multiplied by 26 paydays a year, and then the tax was calculated on an expected income of 780K/year. At a 30% tax rate (rounding the hell out of this) that's 234K in taxes or 9K per pay period, which with my rounding is dam close to the 8.8K in Income tax.

You should get a nice refund at the end of the year.