service performed in the employ of the United States or any instrumentality of the United States, if such service—

(A) would be excluded from the term “employment” for purposes of this title if the provisions of paragraphs (5) and (6) of this subsection as in effect in January 1983 had remained in effect, and

(B) is performed by an individual who— (i) has been continuously performing service described in subparagraph (A) since December 31, 1983 , and for purposes of this clause— (I) if an individual performing service described in subparagraph (A) returns to the performance of such service after being separated therefrom for a period of less than 366 consecutive days, regardless of whether the period began before, on, or after December 31, 1983 , then such service shall be considered continuous, (II) if an individual performing service described in subparagraph (A) returns to the performance of such service after being detailed or transferred to an international organization as described under section 3343 of subchapter III of chapter 33 of title 5, United States Code, or under section 3581 of chapter 35 of such title, then the service performed for that organization shall be considered service described in subparagraph (A), (III) if an individual performing service described in subparagraph (A) is reemployed or reinstated after being separated from such service for the purpose of accepting employment with the American Institute in Taiwan as provided under section 3310 of chapter 48 of title 22, United States Code, then the service performed for that Institute shall be considered service described in subparagraph (A), (IV) if an individual performing service described in subparagraph (A) returns to the performance of such service after performing service as a member of a uniformed service (including, for purposes of this clause, service in the National Guard and temporary service in the Coast Guard Reserve) and after exercising restoration or reemployment rights as provided under chapter 43 of title 38, United States Code, then the service so performed as a member of a uniformed service shall be considered service described in subparagraph (A), and (V) if an individual performing service described in subparagraph (A) returns to the performance of such service after employment (by a tribal organization) to which section 104(e)(2) of the Indian Self-Determination Act applies, then the service performed for that tribal organization shall be considered service described in subparagraph (A); or (ii) is receiving an annuity from the Civil Service Retirement and Disability Fund, or benefits (for service as an employee) under another retirement system established by a law of the United States for employees of the Federal Government (other than for members of the uniformed service);

except that this paragraph shall not apply with respect to any such service performed on or after any date on which such individual performs—

(C) service performed as the President or Vice President of the United States,

(D) service performed— (i) in a position placed in the Executive Schedule under sections 5312 through 5317 of title 5, United States Code, (ii) as a noncareer appointee in the Senior Executive Service or a noncareer member of the Senior Foreign Service, or (iii) in a position to which the individual is appointed by the President (or his designee) or the Vice President under section 105(a)(1), 106(a)(1), or 107 (a)(1) or (b)(1) of title 3, United States Code, if the maximum rate of basic pay for such position is at or above the rate for level V of the Executive Schedule,

(E) service performed as the Chief Justice of the United States, an Associate Justice of the Supreme Court, a judge of a United States court of appeals, a judge of a United States district court (including the district court of a territory), a judge of the United States Court of Federal Claims, a judge of the United States Court of International Trade, a judge or special trial judge of the United States Tax Court, a United States magistrate judge, or a referee in bankruptcy or United States bankruptcy judge,

(F) service performed as a Member, Delegate, or Resident Commissioner of or to the Congress,

(G) any other service in the legislative branch of the Federal Government if such service— (i) is performed by an individual who was not subject to subchapter III of chapter 83 of title 5, United States Code, or to another retirement system established by a law of the United States for employees of the Federal Government (other than for members of the uniformed services), on December 31, 1983 , or (ii) is performed by an individual who has, at any time after December 31, 1983 , received a lump-sum payment under section 8342(a) of title 5 , United States Code, or under the corresponding provision of the law establishing the other retirement system described in clause (i), or (iii) is performed by an individual after such individual has otherwise ceased to be subject to subchapter III of chapter 83 of title 5, United States Code (without having an application pending for coverage under such subchapter), while performing service in the legislative branch (determined without regard to the provisions of subparagraph (B) relating to continuity of employment), for any period of time after December 31, 1983 , and for purposes of this subparagraph (G) an individual is subject to such subchapter III or to any such other retirement system at any time only if (a) such individual’s pay is subject to deductions, contributions, or similar payments (concurrent with the service being performed at that time) under section 8334(a) of such title 5 or the corresponding provision of the law establishing such other system, or (in a case to which section 8332(k)(1) of such title applies) such individual is making payments of amounts equivalent to such deductions, contributions, or similar payments while on leave without pay, or (b) such individual is receiving an annuity from the Civil Service Retirement and Disability Fund, or is receiving benefits (for service as an employee) under another retirement system established by a law of the United States for employees of the Federal Government (other than for members of the uniformed services), or

(H) service performed by an individual— (i) on or after the effective date of an election by such individual, under section 301 of the Federal Employees’ Retirement System Act of 1986, section 307 of the Central Intelligence Agency Retirement Act ( 50 U.S.C. 2157 ), or the Federal Employees’ Retirement System Open Enrollment Act of 1997, to become subject to the Federal Employees’ Retirement System provided in chapter 84 of title 5, United States Code, or (ii) on or after the effective date of an election by such individual, under regulations issued under section 860 of the Foreign Service Act of 1980, to become subject to the Foreign Service Pension System provided in subchapter II of chapter 8 of title I of such Act;