5 CFR § 841.503 - Amounts of employee deductions.
(a) Except as provided in paragraph (b) of this section, the rate of employee deductions from basic pay for FERS coverage is seven percent of basic pay minus the percent of tax which is (or would be) in effect for the payment, for the employee cost of social security.
(b) The rate of employee deductions from basic pay for FERS coverage for a Member, law enforcement officer, firefighter, nuclear materials courier, customs and border protection officer, air traffic controller, member of the Supreme Court Police, Congressional employee, or employee under section 302 of the Central Intelligence Agency Act of 1964 for Certain Employees (who are not FERS RAE or FERS FRAE employees or Members, as defined under § 841.103 of this part), is seven and one-half percent of basic pay, minus the percent of tax which is (or would be) in effect for the payment, for the employee cost of social security.
(c) After December 31, 2012, the rate of employee deductions from basic pay for—
(1) A FERS RAE employee, Member, or Congressional employee is nine and three-tenths percent of basic pay, minus the percent of tax which is (or would be) in effect for the payment, for the employee cost of social security.
(2) A FERS RAE law enforcement officer, firefighter, nuclear materials courier, customs and border protection officer, air traffic controller, member of the Supreme Court Police, or employee under section 302 of the Central Intelligence Agency Act of 1964 for Certain Employees is nine and eight-tenths percent of basic pay, minus the percent of tax which is (or would be) in effect for the payment, for the employee cost of social security.
(d) After December 31, 2013, the rate of employee deductions from basic pay for—
(1) FERS FRAE employee, Member, or Congressional employee is ten and six-tenths percent basic pay, minus the percent of tax which is (or would be) in effect for the payment, for the employee cost of social security.
(2) A FERS FRAE law enforcement officer, firefighter, nuclear materials courier, customs and border protection officer, air traffic controller, member of the Supreme Court Police, or employee under section 302 of the Central Intelligence Agency Act of 1964 for Certain Employees is eleven and one-tenth percent of basic pay, minus the percent of tax which is (or would be) in effect for the payment, for the employee cost of social security.
(e) Employee deductions will be at the rate in paragraphs (a) through (d) of this section as if social security deductions were being made even if social security deductions have ceased because of the amount of earnings during the year, or are not made for any other reason.