For most federal employees, the conversation about retirement service credit focuses on the obvious: years on the rolls, military service deposits, prior federal service that may require a redeposit. Unused sick leave gets a brief mention, if it gets mentioned at all, and the arithmetic that converts your sick-leave balance into additional annuity is almost always a surprise.

It shouldn’t be. Unused sick leave is real service credit, and the conversion is mechanical. The catch is that FERS and CSRS do the conversion differently, and the difference shows up as a real number on the annual annuity line.

The basic rule, common to both systems.

Unused sick leave is added to your creditable service at retirement, with no cap on the number of hours that can be converted. The conversion is done on hours, not days, and the formula is fixed by regulation. The two systems use different multipliers, but the underlying input — your unused sick-leave balance on the day you separate — is the same.

A useful early frame: a federal employee with a healthy sick-leave balance can typically add several months of creditable serviceto their annuity calculation through the conversion. For a 30-year federal employee with 1,200 hours (roughly 150 days, depending on the agency’s daily-hour accounting) of unused sick leave, the converted service can shift the annual annuity by hundreds of dollars a year, for life.

How FERS converts unused sick leave.

FERS converts your unused sick-leave balance into additional service credit by treating the balance as if it were days of service, multiplied by the standard FERS multiplier of 1.0%. The conversion uses a 2,087-hour workyear as the denominator. The formula:

Sick-Leave Credit (FERS) = (Unused Sick-Leave Hours ÷ 2,087) × 1.0% × High-3

For a FERS employee with 1,000 hours of unused sick leave and a $100,000 high-3:

  • 1,000 ÷ 2,087 = 0.479 years of additional service
  • 0.479 × 1.0% × $100,000 = $479 per year of additional annuity, for life

For an employee with 2,000 hours of unused sick leave and the same high-3, the answer is roughly $958 per year. For an employee with the maximum allowed balance, which varies by agency but is often in the 2,000–2,500-hour range, the answer can approach $1,200 per year in additional annuity.

How CSRS converts unused sick leave.

CSRS does the same conversion but uses the standard CSRS multiplier of 1.5%on the converted balance. The two-tier structure of the CSRS formula (1.5% on the first 5 years, 1.75% on years beyond) is preserved — the sick-leave conversion drops into the formula at the appropriate tier based on the employee’s total service.

The practical effect: a CSRS employee with the same sick-leave balance and the same high-3 receives a meaningfully larger annuity boost than a FERS employee. That is consistent with the more generous overall CSRS formula, and it is the reason the CSRS sick-leave conversion is sometimes described as “more valuable per hour.”

For a CSRS employee with 1,000 hours of unused sick leave, a $100,000 high-3, and a service total that places the converted balance in the 1.5% tier (i.e., total service plus converted service remains at or under 5 years when the sick leave is added at the front of the calculation):

  • 1,000 ÷ 2,087 = 0.479 years of additional service
  • 0.479 × 1.5% × $100,000 = $719 per year of additional annuity, for life

For a CSRS employee whose converted balance drops into the 1.75% tier (i.e., total service plus converted service exceeds 5 years), the per-hour value is higher. Using the same 1,000 hours and the same $100,000 high-3:

  • 0.479 × 1.75% × $100,000 = $838 per year of additional annuity, for life

What the conversion is not.

A few things the sick-leave conversion is commonly confused with, and isn’t:

  • It is not a payout at retirement. You do not receive a lump sum for unused sick leave. The hours convert to service credit that increases your monthly annuity.
  • It is not counted toward the age-and-service thresholds for retirement eligibility. You cannot retire earlier because you have a large sick-leave balance. The credit applies only to the annuity calculation, not to the eligibility rule.
  • It is not a basis for the FERS supplement. The supplement is calculated on actual years of creditable service, and sick-leave hours are not included in that calculation.
  • It is not a basis for the FERS 1.1% age-62 multiplier. The 1.1% applies to the first 20 years of creditable service, and sick-leave service does count toward the 20-year threshold — which is one of the few places where sick-leave conversion interacts with another retirement rule.

When the conversion can shift a real decision.

The sick-leave conversion is mechanical, but the inputs are not always clean. The decisions that move real money:

1. Timing the retirement to the day.

Your unused sick-leave balance is calculated as of the day you separate. If you use 8 hours of sick leave in the final month of your career, your converted service credit is reduced by however many hours you used. For employees with large balances, the day-by-day precision of the timing decision can move the annual annuity by tens of dollars a year, for life.

2. The interaction with the high-3.

The high-3 is calculated on your highest 36 consecutive months of basic pay. The sick-leave conversion adds to your service, not to your high-3. But because the annuity is the product of the multiplier, the service, and the high-3, the conversion is more valuable when the high-3 is high. A promotion in the final 36 months of service that lifts the high-3 also lifts the marginal value of every sick-leave hour you have left to convert.

3. The interaction with the 80% cap under CSRS.

For CSRS employees approaching the 80% cap, sick-leave conversion can be the difference between hitting the cap and not. An employee whose standard formula would produce, say, 78% of high-3 may find that the sick-leave conversion pushes the calculated annuity above 80%, triggering the cap and producing a smaller-than-expected marginal benefit. It is worth running the arithmetic both ways.

A few notes on the inputs.

The 2,087-hour workyear used in the conversion is the standard figure OPM uses for most general-schedule employees, but it is not universal. Employees on compressed schedules, uncommon tours of duty, or other workyear structures may have a different denominator. The agency HR specialist who processes your retirement application is the source of truth for the conversion.

The sick-leave balance used in the conversion is the balance on the day of separation, and it includes any sick leave that was restored (e.g., from a previous forfeiture) under your agency’s leave system. The conversion is done in whole hours, with fractions rounded per OPM rules.

The plain summary.

Unused sick leave is real service credit. FERS values it at 1.0% of high-3 per converted year; CSRS values it at 1.5% or 1.75% per converted year, depending on the tier. The conversion is calculated on hours, uses a 2,087-hour workyear as the denominator, and is added to your creditable service on the day you separate. It does not affect retirement eligibility, the FERS supplement, or the basic FERS 1.0% multiplier — but it does affect the FERS 1.1% age-62 threshold, the CSRS 80% cap, and the final annuity figure on the page.

The arithmetic is mechanical. The decision to use or save sick leave in the final months of a career is not.