The Leave Year Trap: What Retiring in January Costs

Retiring in late December feels like a clean break — you finish the year, you leave. Retiring in early January feels like the same thing. The two dates are not the same thing. Four separate calendar-based rules attach money to the turn of the year, and they pull in different directions. Getting them wrong by a single day can forfeit a full month of pension.

The Best Date to Retire Calculator ranks candidate dates against all four rules at once. This guide explains what each rule does and why January is where they conflict most sharply.

The Four Rules

Rule 1 — The Annuity Commencing Date (5 U.S.C. § 8464(a))

A FERS annuity commences on the first day of the month after the month of separation. There is no exception for separating early in a month. Separate on December 31 and your annuity begins January 1 — the very next day. Separate on January 1 and your annuity begins February 1. That one day of extra federal service costs you the entire month of January's pension.

CSRS has the same first-of-the-following-month rule under 5 U.S.C. § 8345(b)(1)(A), with one addition: 5 CFR 831.701(b)(3) starts a CSRS annuity the day after separation when the employee served three days or fewer in the month of retirement. There is no FERS counterpart to that three-day rule anywhere in 5 CFR part 842. FERS retirees cannot use it.

This is the rule that makes December 31 the canonical last day for FERS employees who want their annuity to begin January 1. Working one day into January pushes the commencing date to February 1.

Rule 2 — The Leave Year Ceiling (5 U.S.C. § 6304)

Annual leave above the carryover ceiling — 240 hours for most employees, 360 hours for certain overseas posts, 720 hours for SES and senior-level positions — is forfeited at the beginning of the first full biweekly pay period of the next calendar year. That boundary is not January 1. It is the start of the first full pay period of the new year, which OPM publishes on its leave year calendar.

For leave year 2026, that boundary falls on January 11, 2026. Leave year 2026 ends on January 9, 2027. Every boundary is 14-day arithmetic from the OPM-anchored grid, not from January 1.

An employee who retires before that boundary — say, December 31 — receives a lump-sum payment for their full accrued leave balance under 5 U.S.C. § 5551(a), including any hours above the ceiling that have not yet been forfeited. An employee who works past the boundary without reducing their balance below the ceiling loses the excess permanently. The lump sum equals the pay the employee would have received had they remained in service through the projected leave period, projected over workdays and holidays from the day after separation under 5 CFR 550.1204. Any statutory pay adjustment effective inside that period applies on and after its effective date under 5 CFR 550.1205.

Rule 3 — The January Pay Raise

The annual pay adjustment takes effect on the first day of the first full biweekly pay period of the new calendar year — the same pay-period boundary that sets the leave year ceiling. In 2026, that is January 11.

This matters for two separate calculations. First, the lump-sum leave payout: hours that fall on or after January 11 in the projected leave period are paid at the new, higher rate under 5 CFR 550.1205. An employee who retires December 31 with a large leave balance will have a portion of that payout calculated at the new rate. Second, the high-3 average salary: if the raise lands inside the three-year averaging window, it raises the high-3 and therefore the annuity base. Retiring a few weeks before the raise takes effect can mean the raise never reaches the high-3 at all — or reaches it only partially, weighted by the days it was held on a 360-day year under 5 U.S.C. § 8401(3). The guide Why Your Agency's Pension Estimate Is Too High works through exactly how OPM weights each pay rate by the days held, and why the agency's shortcut overstates the result.

Rule 4 — The First COLA in Twelfths (5 U.S.C. § 8462)

The FERS cost-of-living adjustment is effective December 1 each year and first paid in January. The first COLA an annuitant receives is prorated in twelfths of the months the annuity has been payable, capped at 12 twelfths. An annuity that commenced January 1 has been payable for 12 months by December 1 and receives the full COLA. An annuity that commenced February 1 has been payable for 11 months and receives 11 twelfths of the COLA. An annuity that commenced March 1 receives 10 twelfths, and so on.

The difference between a full and a partial first COLA is permanent: adjustments withheld before age 62 are never made up under 5 U.S.C. § 8462(c)(3), and the proration shortfall in the first year compounds into every later year's base.

A Worked Example: One Day, One Month of Pension

Consider a FERS employee with 30 years of creditable service and a high-3 average salary of $95,000. The basic annuity under 5 U.S.C. § 8415(a) accrues at 1% per year of service.

Annuity = $95,000 × 1.0% × 30 = $28,500 per year, or $2,375 per month.

Scenario A — Separation December 31: Annuity commences January 1. The employee collects $2,375 in January.

Scenario B — Separation January 1: Annuity commences February 1. The employee collects nothing in January. The first check arrives in February.

The cost of working one extra day: $2,375 — one full month of pension, gone. The pension itself is identical in both scenarios; only the commencing date differs, and that one-day difference forfeits January entirely.

Add the COLA proration: in Scenario A, the annuity has been payable 12 months by December 1 and receives the full first COLA. In Scenario B it has been payable 11 months and receives 11 twelfths. The gap in the first COLA payment is smaller than the lost month, but it persists in every subsequent year's base.

Add the leave balance: if this employee carries 300 hours of accrued leave into December and the leave year ceiling is 240 hours, retiring December 31 pays out all 300 hours in the lump sum. Working into January past the leave-year boundary forfeits 60 hours permanently before the lump sum is even calculated.

Which Days Are Safe

For most FERS employees, the safest retirement dates near the year turn are:

• December 31 — annuity commences January 1, full first COLA, leave balance paid before the forfeiture boundary.
• The last day before the leave-year boundary — if the boundary falls after January 1 (as it does in most years), retiring on that day preserves the leave balance and still allows a February 1 or later commencing date, though the one-month pension gap from Rule 1 still applies.

No single date satisfies all four rules perfectly for every employee. The right answer depends on your leave balance, your proximity to the pay-raise effective date, your high-3 window, and whether you are FERS or CSRS. The Best Date to Retire Calculator scores each candidate date against all five rules — including the CSRS three-day rule that FERS does not have — and shows which one maximizes your total first-year income.

What This Guide Does Not Cover

This guide addresses the calendar mechanics of the commencing date, the leave year, the pay raise, and the COLA proration. It does not cover: MRA+10 reductions of 5% per year under age 62 under 5 U.S.C. § 8415(h)(1); the high-3 computation in detail; sick leave conversion credit; survivor elections; or the FERS supplement earnings test. It applies to standard FERS and CSRS retirements only — special provisions employees under 5 U.S.C. § 8412(d) and (e) have different mandatory separation ages and should verify their own leave-year boundaries.

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This guide is informational only and does not constitute financial, tax, or legal advice. Last reviewed: August 2026.

Frequently asked questions

Does working one day into January really cost a full month of pension?

Yes, under 5 U.S.C. § 8464(a). A FERS annuity commences on the first day of the month after the month of separation, with no exception for separating early in a month. Separating January 1 instead of December 31 moves the commencing date from February 1 — the pension for January is simply never paid.

Is the leave year boundary the same as January 1?

No. The leave year ends the day before the first full biweekly pay period of the next calendar year, which OPM publishes on its leave year calendar. For leave year 2026, that boundary is January 9, 2027, and the new leave year begins January 11, 2026. The forfeiture of excess leave happens at that boundary, not at midnight on December 31.

Does the CSRS three-day rule help FERS employees?

No. The rule at 5 CFR 831.701(b)(3) — which commences a CSRS annuity the day after separation when three or fewer days were served in the retirement month — has no counterpart in 5 CFR part 842, which governs FERS. FERS retirees always wait for the first of the following month regardless of when in the month they separate.

How does the January pay raise affect the lump-sum leave payout?

Under 5 CFR 550.1205, any statutory pay adjustment effective inside the projected leave period applies on and after its effective date. Hours in the lump-sum projection that fall on or after the raise's effective date are paid at the new rate. An employee who retires December 31 with a large leave balance will have a portion of the payout calculated at the higher January rate, because the projected leave period extends into January.

Does the first COLA proration matter much in dollar terms?

The proration itself may be modest in the first year, but it is permanent. Under 5 U.S.C. § 8462(c)(3), adjustments withheld before age 62 are never made up, and the shortfall in the first year's COLA base carries forward into every subsequent year's calculation. An annuity that commenced February 1 instead of January 1 receives 11 twelfths of its first COLA rather than the full amount, and that smaller base is what every future COLA compounds from.

This guide is informational only. It is not financial, tax, or legal advice, and FedAnnuity is not affiliated with OPM or the U.S. government. Retirement rules turn on the specific facts of a career, and only your agency and OPM can give you a binding figure.

Last reviewed: August 2026 · Against primary sources cited in the body.