Will Congress cause your Paycheck to be incorrect?
Unless congress acts by December 10, your paycheck may or may not be correct. It all depends on the if the Bush-era tax cuts are extended. If they are extended to some degree, which most expect that they will be the IRS may not have enough time to update the information used by your payroll department to withhold the correct amount of tax from your paycheck.
See this for more infomation –
Senate tax-vote delay causes headaches for payroll departments