The Best Day to Retire Under FERS: The Month-End Rule, the Leave-Year Play, and a Checklist That Beats Any Magic Date

Federal holidays current as of 2026 · Sources: OPM · U.S. Office of Personnel Management

Free calculator · No account required

Federal Holiday Leave Optimizer →

See which days of leave create the longest stretches of time off around 2026 and 2027 federal holidays.

The commencement rule, defined: For a regular immediate FERS retirement, the annuity commences on the first day of the first full month after separation. There is no partial-month annuity — separate on March 1st and your pension starts April 1st, exactly as if you'd worked to March 31st. (CSRS retains a 3-day grace rule; FERS has none.)

Who This Article Is For

• Feds who've picked their retirement year and now need the actual date
• Employees who've seen "December 31" on every best-dates list and want to know why — and when it's wrong
• Anyone about to file with a mid-month date who doesn't realize what it costs
• Planners deciding between "one more month" and "start the pension now"
• Final-year employees who want their remaining leave to buy the most calendar possible

1. The Month-End Rule: Where Almost All the Money Is

Because the annuity starts the first day of the month after separation, the calendar does something unusual: all days of a month are not equal.

Illustrative example. $95,000 salary (≈ $260/day of gross pay), earned annuity of $28,500/year ($2,375/month). Not financial advice.

Separating March 1 instead of February 28 trades a $2,375 pension month for $260 of salary — the single most expensive small mistake in retirement filing. The general principle: work to a month's end, or don't start that month at all. Every day you work past the 1st is fine if you continue to the month's last day, because salary nearly always exceeds the annuity it displaces; the only bad dates are the early-to-mid-month ones.

2. The Four-Test Checklist

The best dates pass all four tests simultaneously; a merely good date passes the first two.

1. Last day of a month — starts the annuity immediately (the rule above).
2. End of a pay period — leave accrues only for completed pay periods. Separate mid-period and the final 4–8 hours of annual and sick accrual evaporate. Month-ends that are also pay-period-ends are the calendar's sweet spots — your HR calendar shows which.
3. At or after every milestone. Date polish is worth hundreds; milestones are worth thousands. Never let a "good date" pull you ahead of your MRA (even by days — the retirement category isn't available yet), your 62nd birthday if you're near it (the 1.1% multiplier at 62+20 is a 10% larger pension for life), a WGI that lifts your High-3, or the 30-year mark.
4. End of the leave year, if the payout matters to you. The leave year ends in early January — the one date where you can hold the 240-hour carryover plus an entire year's fresh accrual, all cashed at your final rate.

3. Why Late December / Early January Dominates

The famous year-end dates stack four separate wins onto one filing:

• Maximum lump sum. Retiring at (or just before) the leave-year's end captures up to ~448 hours of annual leave — a payout north of $24,000 for a senior GS-12/13.
• The raise rides the payout. The lump sum is projected forward from your separation date — leave hours projected past the January raise's effective date are paid at the new year's higher rate.
• A cleaner tax year. Retire December 31 and the lump sum lands in January — a year whose income is annuity-sized, not salary-sized. The same payout received mid-career-year stacks on ten months of salary at your top marginal rate.
• An immediate annuity. December 31 is a month-end: the pension starts January 1 with nothing skipped.

The honest caveats: a December date means OPM processes your case in its busiest season (expect the interim-payment period — partial annuity while your case is finalized — to run longer), and "everyone retires December 31" is precisely why. None of that changes the math; it changes your patience requirements. Budget for a few months in which OPM pays interim (reduced) annuity before the full amount and back pay arrive.

When December is the wrong answer: a milestone that lands mid-year outranks the leave-year play (retiring the month-end after your 62nd birthday in June beats waiting for no reason — or worse, going before it for a date); health, family, or a burned-out final year are real inputs; and if your leave balance is modest, the year-end premium mostly isn't there.

4. Spending the Final Year Well: Bridges, Not Dribbles

Your last year has two competing goals: arrive at the date with a maximum annual-leave balance, and actually enjoy the year. The resolution is efficiency — buy the most days off per leave day spent. That's what federal holidays are for:

• Monday/Friday holidays are free 3-day weekends — zero leave.
• Tuesday/Thursday holidays bridge with a single leave day into 4-day weekends.
• Thanksgiving week: 4 leave days buy 9 consecutive days off.
• The Christmas–New Year cluster: 3–4 leave days typically buy a stretch of 10+ days — and for a December 31 retiree, leave scheduled here is a near-free victory lap, since every unspent hour is getting cashed out anyway. (One rule to respect: the lump-sum payout can't begin until your last duty day — talk to HR about how terminal leave is handled; you generally can't be "on leave" past your separation date.)

Our Holiday Leave Optimizer ranks every bridge in 2026 and 2027 by days-off-per-leave-day and fits them to a leave budget — useful in any year, sharpest in your last one.

5. Common Date Mistakes

1. Retiring on the 1st or 2nd of a month. One or two days of salary; a full month of annuity forfeited.
2. Separating mid-pay-period. The final partial period accrues no leave — a small, fully avoidable loss.
3. Filing for a date days before a milestone. Days before your MRA date, your 62nd birthday, or a 30-year anniversary are the most expensive days on the calendar to not work.
4. Ignoring the interim-pay gap. Whatever your date, the first full annuity payment takes months. Keep a cash buffer; December filers should keep a bigger one.
5. Treating the "magic date" as mandatory. The best-dates lists optimize dollars, not lives. A date that passes tests 1–3 and fits your life beats a perfect date that doesn't.

Frequently Asked Questions

When does a FERS annuity start? The first day of the month after your separation. Retire January 31 → annuity begins February 1. There's no partial-month annuity and no FERS grace period.

Is December 31 really the best day to retire? It's the date that most often stacks every advantage: month-end (immediate annuity), near the leave-year end (maximum payout), lump sum paid at the new year's raised rate, and payout taxed in a low-income year. It's not better than a mid-year milestone you'd otherwise miss.

What happens if I retire in the middle of a month? You collect salary through your separation date, but no annuity for that month — the pension starts the 1st of the following month. Mid-month dates trade a month of pension for days of salary.

Why does the end of the pay period matter? Annual and sick leave accrue only for completed pay periods. Separating mid-period forfeits that period's accrual.

When is the federal leave year end? Early January — the end of the last full pay period that begins in the calendar year. The exact date shifts annually; your payroll calendar (or HR) has it.

How long until my full annuity arrives? OPM typically pays interim (partial) annuity while it finalizes your case — commonly a few months, longer in the post-December surge. The balance arrives as back pay.

Should I burn my annual leave before retiring or take the payout? Hours you don't use are cashed at your final (highest) rate — and if you retire at year-end, at the next year's rate. Use leave you'll genuinely enjoy; the rest is usually worth more as the check. Note that you can't remain on terminal leave past separation to stretch the calendar.

Does the FERS Supplement start with the annuity? Yes — eligible retirees' supplement runs with the annuity from commencement (and, like the annuity, arrives in full only after OPM finalizes the case). See the supplement guide for eligibility.

The Bottom Line

There is no secret date — there's one commencement rule and four tests. Separate on a month's last day so the pension starts the next morning; make it a pay period's end so the last accrual posts; never let date-polish jump ahead of a milestone worth real money; and if you want the maximum check on the way out, let the leave year pick your December. Then spend the final year's leave like the scarce currency it is — on bridges, not dribbles — and walk out with the calendar, the payout, and the pension all pointing the same way.

---