Shortly after the President signed the fiscal cliff deal into law, the IRS issued updated income tax withholding tables to reflect the changes made by the measure. Among other provisions, the American Taxpayer Relief Act of 2012 allows Social Security payroll taxes to return to 6.2%. The revised IRS Notice 1036 (pdf) includes the percentage method income tax withholding tables and related guidance that employers will need to adjust their payroll procedures.

In a news release, the IRS advises employers to

start using the revised withholding tables and correct the amount of Social Security tax withheld as soon as possible in 2013, but not later than Feb. 15, 2013. For any Social Security tax under-withheld before that date, employers should make the appropriate adjustment in workers' pay as soon as possible, but not later than March 31, 2013.

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