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Missing Out on the Full High-3 Could Quietly Cost You Thousands Every Single Year in Retirement

Missy E
November 14, 2025

Key Takeaways

Overlooking certain pay types in your high-3 salary calculation can result in a significantly lower federal retirement annuity.
Timing, job changes, and even voluntary downgrades can reduce your high-3 average without you realizing until it’s too late.

Understanding What the High-3 Salary Is and Isn’t

Your “high-3” salary refers to the average of your highest-paid 36 consecutive months of basic pay. Under FERS and CSRS, this high-3 is the foundation for calculating your annuity. But here’s where many government employees are caught off guard: not every form of compensation is counted.

Basic pay includes:

Base salary
Locality pay
Shift differentials (only in certain circumstances)

What doesn’t count:

Overtime pay
Bonuses
Awards
Travel reimbursements
Hazard pay (in most cases)

This distinction is critical. If you’ve been relying on overtime or bonuses to boost your annual income, your high-3 won’t reflect that extra effort.

Why the High-3 Matters More Than You Think

Your retirement annuity under FERS is generally 1% of your high-3 salary multiplied by your years of creditable service. For those retiring under special provisions, such as law enforcement or air traffic controllers, the multiplier is 1.7% for the first 20 years and 1% thereafter.

Let’s say you worked for 30 years under FERS and your high-3 average is $90,000. Your annual annuity would be $27,000. But if your actual earnings hovered closer to $100,000 due to overtime or bonuses, that extra $10,000 isn’t helping you. And that’s a permanent gap you can’t fix once you’re retired.

Common Mistakes That Lower Your High-3

1. Job Switching Late in Career

If you switch to a lower-paying role in your final years, even for personal reasons or reduced stress, it could impact your high-3 average. Since the high-3 is based on 36 consecutive months, a single lower year near retirement can displace a higher-earning period.

2. Taking a Voluntary Downgrade

Some employees shift into less demanding roles as they approach retirement. While this can be appealing, it may result in lower pay during your last three years—and therefore a smaller annuity.

3. Using Comp Time or Leave Without Pay (LWOP)

Extended leave without pay, such as during a family emergency or for temporary disability, reduces your salary for those months. If those months fall within your highest-paid three years, they drag down your average.

4. Relying on Temporary Promotions

Temporary promotions are usually not enough to create a full 36-month period at the higher salary. If your high-earning role lasts only 12 or 24 months, it may not be enough to offset earlier lower-pay months.

Timing Retirement Around the High-3

Your retirement date matters. The difference between retiring on December 31 versus waiting until March 31 could give you three extra months of higher pay in your high-3 window. These months could displace lower ones earlier in the calculation.

Similarly, if you’re in line for a within-grade increase, general pay raise, or locality adjustment, postponing retirement for a few months could raise your high-3 significantly.

Strategies to Maximize Your High-3

Review Your Earnings Record

Go back at least 10 years and map out your pay history. Identify the 36 consecutive months where your basic pay was the highest. This will not always be your last three years.

Delay Retirement If Needed

If you recently got a promotion or locality adjustment, working a bit longer ensures those months count in your high-3. Retirement is permanent. A few extra months can make a lifetime difference in your annuity.

Avoid LWOP During High-3 Period

If you know your high-3 window includes the current year, limit any unpaid time off. Even partial months at lower earnings reduce your total average.

Consider Acting Assignments Carefully

While temporary promotions may help with job experience or networking, they usually won’t last the 36 months needed to fully impact your high-3. Don’t count on them unless they become permanent.

Understanding the Limits of High-3 Planning

Even with strategic planning, there are limits to how much you can affect your high-3. Here’s what to keep in mind:

You can’t average non-consecutive months. The 36 months must be back-to-back.
You can’t include income that isn’t basic pay. This excludes bonuses, awards, or overtime regardless of how regularly you received them.
You can’t change the calculation retroactively. Once your retirement claim is processed, the high-3 is locked in.

When to Start Thinking About Your High-3

Ideally, you should start evaluating your high-3 at least 5 years before you plan to retire. Why?

You may still have time to increase your earnings
You can avoid decisions that unintentionally reduce your average
You can compare scenarios (such as different retirement dates) to see the long-term effects

Don’t assume your agency will optimize this for you. It’s your responsibility to verify your salary records, catch errors, and assess how your decisions affect your annuity.

How the High-3 Differs for CSRS Employees

If you’re covered by CSRS, the high-3 rule is the same—but the impact is amplified. CSRS annuity formulas are more generous, often providing 55-80% of your high-3 depending on years of service.

That means:

A drop in your high-3 has a magnified effect
Each thousand dollars you miss in your high-3 could mean $550 to $800 less annually

If you’re among the dwindling group of CSRS employees still in the system, getting the full value out of your high-3 is even more essential.

Is the High-3 Always the Last 3 Years?

No. It only has to be the highest 36 consecutive months. That could be:

Mid-career, if you had a peak assignment
Three years before a downgrade or life event
Any rolling 3-year period that yields the highest average

You have the right to request a recalculation if you think your agency used the wrong period. But proving it requires documentation and proactive follow-up.

Why You Shouldn’t Rely on Estimators Alone

Online calculators and agency-provided retirement estimates often assume your last 3 years are your high-3. That’s not always true. If you had higher earnings earlier, the default estimates may shortchange your projected annuity.

Validate the calculation manually or speak with your agency’s HR and retirement specialists. It’s not uncommon for incorrect assumptions to persist until you’re already retired.

The Long-Term Cost of a Lower High-3

Here’s what’s at stake:

$1,000 less in your high-3 could reduce your annual annuity by $300 to $800, depending on your service and retirement system.
That could mean $9,000 to $24,000 less over a 30-year retirement.
Multiply that by additional gaps in your high-3, and the cumulative loss is substantial.

This is why it’s not just a technicality—it’s a decision that compounds for decades.

Don’t Let the High-3 Work Against You

The high-3 average may sound like a fair, simple system. But unless you take the time to understand its exclusions and actively manage when and how it applies, you could find yourself with a lower-than-expected annuity.

If you’re within five years of retirement, now is the time to: