Social security tax rate for 2012.   The employee social security tax rate is 4.2% and the employer social security tax rate is 6.2% (10.4% total). Be sure to use the correct rate when reporting corrected amounts reported on Form 943-X, line 6.

Qualified employer's social security tax credit.   Qualified employers were allowed a credit of their share (6.2%) of social security tax on wages paid to qualified employees after March 18, 2010, and before April 1, 2010. Any errors discovered on a previously filed 2010 Form 943 for this credit are corrected on Form 943-X, lines 16c and 16d.

Qualified employer’s social security tax exemption expired.   The qualified employer's exemption for their share (6.2%) of social security tax on wages paid to qualified employees expired on December 31, 2010. Any errors discovered on a previously filed 2010 Form 943 for this exemption are corrected on Form 943-X, lines 9a and 9b.

Advance payment of earned income credit (EIC).   The option of receiving advance payroll payments of EIC expired on December 31, 2010. Any errors discovered on a previously filed Form 943 for a tax year ending before January 1, 2011, are corrected on Form 943-X, line 15.

COBRA premium assistance credit.   Employers who make COBRA premium assistance payments for assistance eligible individuals are allowed a credit for the payments on Form 943. Any errors discovered on a previously filed Form 943 for this credit or for the number of individuals provided COBRA premium assistance are corrected on Form 943-X. See the instructions for lines 16a and 16b, later.