(a)(1) The basic annuity of an employee who elected FERS coverage is an amount equal to the sum of the accrued benefits under CSRS as determined under paragraph (b) of this section and the accrued benefits under FERS as determined under paragraph (c) of this section.

(2) The computation method described in paragraph (a)(1) of this section is used in computing basic annuities under part 842, subpart D of this chapter, survivor annuities under part 843, subpart C of this chapter, and the basic annuities for disability retirement under subchapter V of chapter 84 of title 5 United States Code.

(3) An annuity computed under this paragraph is deemed to be the individual's annuity under FERS.

(b)(1) Except as provided in paragraphs (b)(2) and (b)(3) of this section and § 846.305, accrued benefits for civilian service as described in § 846.302(c), and military service as described in § 846.303(b) are computed under CSRS provisions.

(2) Reductions to provide survivor benefits required under part 831, subpart F of this chapter, and the 50-percent minimum annuity for air traffic controllers described in 5 U.S.C. 8339(e) do not apply to accrued benefits under this paragraph.

(3) Sick leave creditable under § 831.302 of this chapter is equal to the number of days of unused sick leave to an individual's credit as of the day of retirement, death, or as of the effective date of the election of FERS coverage, whichever is the lesser amount of sick leave, for an individual who—

(i) Retires under §§ 842.204, 842.205, 842.206, 842.207, 842.208, 842.209, 842.210, or 842.211 of this chapter;

(ii) Dies leaving a survivor eligible for a monthly FERS survivor annuity under § 843.310 or § 843.311 of this chapter; or

(iii) After retiring for disability, becomes entitled to an annuity computation under part 842, subpart D of this chapter.

(c) Accrued benefits are computed under FERS for the following service:

(1) Creditable civilian service performed on or after the effective date of the election of FERS coverage;

(2) Creditable civilian service other than as described in § 846.302(c); and

(3) Creditable military service other than that described in § 846.303 (b) and (c).

(d)(1) Except as specified in § 846.305, the average pay for computations under paragraphs (b) and (c) of this section is the largest annual rate resulting from averaging the individual's rates of basic pay in effect over any 3 consecutive years of creditable service or, in the case of an annuity based on service of less than 3 years, over the total period of creditable service, with each rate weighted by the period it was in effect.

(2) For the purposes of paragraph (d)(1) of this section, service is considered creditable if it is creditable under either CSRS or FERS.

(e)(1) The cost-of-living adjustments for the annuities of individuals electing FERS coverage are made as follows:

(i) The portion of the annuity computed under paragraph (b) of this section is adjusted as provided under CSRS.

(ii) The portion of the annuity computed under paragraph (c) of this section is adjusted as provided under FERS.

(2) An annuity initially payable to an annuitant's survivor (other than a child under part 843, subpart D of this chapter) is increased by the total percent by which the annuitant's annuity was increased under this paragraph. Thereafter, the survivor annuity is adjusted for cost-of-living increases under 5 U.S.C. 8462.

(f) In computing an annuity under paragraph (a) of this section for an employee retiring under § 842.204(a)(1) or § 842.212(b) of this chapter, any reduction for age required by § 842.404 of this chapter applies to the sum computed under paragraph (a) of this section. No reduction under CSRS is applicable.

(g) In computing an annuity under paragraph (a) of this section for an employee retiring early under § 842.205 of this chapter or involuntarily under § 842.206 of this chapter, the reduction for age required by 5 U.S.C. 8339(h) applies to the portion of the annuity computed under CSRS provisions.

(h) In computing an annuity under paragraph (a) for an employee retiring as a firefighter or law enforcement officer under § 842.208 of this chapter or as an air traffic controller under § 842.207 of this chapter, there is no applicable reduction for age.

(i) An annuity supplement under part 842, subpart E of this chapter, is computed using the same civilian service used for the computation under paragraph (c) of this section.

(j) An alternative form of annuity for a basic annuity computed under paragraph (a) of this section is computed as follows:

(1) The alternative benefit for the portion of the annuity computed under paragraph (b) of this section is computed under CSRS as provided in part 831, subpart V of this chapter, except that a refund of CSRS contributions based on a refund application filed after the individual elects FERS coverage may not be deemed to be redeposited under § 831.2206 of this chapter if the individual is entitled to a deferred annuity under § 842.212 of this chapter.

(2) The alternative benefit for the portion of the annuity computed under paragraph (c) of this section is computed under FERS as provided in part 842, subpart G of this chapter.