This is what we got from our payroll department yesterday:
Hello,
I just wanted to warn everyone that the tax rates have changed effective 1/1/11....
You will see more money withheld for taxes with this change. I have attached a copy of the IRS Tax Notice.
If you want to calculate your withholding you would use Table 4 on the notice. You will take your Monthly Withhold Gross and subtract $308.33 for each dependent that you claim on your W-4 and this will give you the taxable amount.
Attached was IRS Notice 1036. We get paid monthly, so I calculated a $75 reduction in my salary. We'll find out if I was about right at the end of next week.
ETA: I work in education too and don't pay into Social Security. For those that do, the SS contribution is going down, which should offset some of this, but not for us.