A benefits specialist at a regional federal office pulls her annual enrollment report and notices something odd. On the second floor, the investigators and analysts are almost all contributing, and most are putting in 6% or more. On the first floor, the intake and records staff are mostly parked at exactly 3%, with a handful at zero. Same building. Same retirement system. Same match. Wildly different outcomes.

She isn't imagining it, and her office isn't unusual. Participation in the Thrift Savings Plan varies a lot across the federal government, and the single national number most people quote hides most of that story.

The headline number and what it leaves out

For FERS employees, participation has generally run in the high 80s as a percentage, according to Federal Retirement Thrift Investment Board reporting. That is strong by private-sector standards. CSRS employees, who get no agency match, participate at lower rates. Uniformed services members have historically participated at lower rates still, though the Blended Retirement System has pushed those numbers up. Exact figures shift every year, so check the participant statistics at tsp.gov rather than trusting any number frozen in an article.

Now the catch. "Participation" can mean at least three different things:

  • Anyone with a TSP account balance
  • Anyone currently making contributions
  • Anyone contributing enough to capture the full agency match

Those three groups are very different sizes. A workforce can post a 90% participation rate and still have a third of its people leaving free money unclaimed.

Why agencies differ

Agency-level differences rarely come from agency policy, since the TSP rules are the same everywhere. They come from who works there and how they work.

Pay grade and age

This is the biggest driver. An employee at GS-5 with student loans, a new apartment, and a rent check that eats half of take-home pay will contribute less than a GS-13 who has been on the job for 15 years. That is not a failure of financial literacy. It is arithmetic.

Agencies with a large share of entry-level, clerical, or technical positions tend to show lower contribution rates. Agencies heavy on mid-career professionals, attorneys, engineers, and scientists tend to show higher ones.

Turnover and tenure

High-turnover workforces hurt participation numbers. Someone three months into a job is still sorting out health insurance, a commute, and a security clearance. TSP contributions can slide down the list. Agencies with long average tenure, where people are watching their FERS pension estimate grow, tend to treat the TSP as a serious project.

Retirement system mix

An agency with a large CSRS population will see different numbers than one staffed almost entirely by FERS employees, because CSRS has no match. Likewise, a military-heavy workforce reflects the BRS rules, where the match starts around the beginning of the third year of service. People who joined before 2018 are mostly under the legacy system with no match at all.

Workforce culture and communication

This one is harder to measure but easy to spot. Some agencies hold regular retirement seminars, have HR staff who explain the match in plain language, and encourage supervisors to mention it. Others hand over a packet on day one and never mention it again. Shift workers, field staff, and people without regular desk access to email are the easiest to miss.

The 3% default and the match gap

Automatic enrollment has been a real success. Since 2010, new FERS hires have been enrolled at 3% unless they opt out, and most stay in. That moved participation up sharply among new employees.

But defaults stick. Here is why that matters in dollars.

Under FERS, the agency contributes 1% of salary automatically. It then matches the first 3% you contribute dollar for dollar and the next 2% at 50 cents on the dollar. Contribute 5% and you get the full 5% from the agency.

Take an employee earning $50,000:

  • At the 3% default, she contributes $1,500. The agency adds $500 (the automatic 1%) plus $1,500 (the match), for $2,000.
  • At 5%, she contributes $2,500. The agency adds $500 plus $1,500 plus $500, for $2,500.

Moving from 3% to 5% costs her an extra $1,000 a year before tax, and the agency adds another $500 on top. That is a 50% return before any market growth. Multiply it across a few thousand employees at one agency, and you can see why benefits offices focus on this gap more than on the raw participation rate.

How to read agency comparisons

If you come across a chart ranking agencies by TSP participation, a few cautions apply.

First, check what is being measured. Account holders, active contributors, and full-match contributors are not interchangeable.

Second, look at the workforce composition. An agency that ranks low may simply be young, lower-graded, or newly hired in large numbers. That is a different problem from an agency where mid-career, well-paid people are skipping the plan.

Third, remember that averages hide spread. An agency with a 75% contribution rate might have a narrow middle or a split between two very different groups.

For context, OPM's workforce data site lets you look at age, grade, and tenure by agency. Pairing that with TSP participation figures, where available, is a better way to understand what is going on than a ranking alone.

What this means if you work for the government

You do not need your agency's numbers to act on your own. A few practical checks:

  1. Look at your current contribution rate in your TSP account or your agency's payroll system. If it is the default 3%, you are probably missing part of the match.
  2. Confirm you are getting the full match. Under FERS that means contributing at least 5% of basic pay.
  3. Raise it with your next pay raise. Many people find it painless to send half of each raise to the TSP before it ever shows up in take-home pay.
  4. Check the annual limit. The IRS sets the elective deferral limit every year, with higher catch-up amounts for people 50 and older. Look it up at irs.gov or tsp.gov before you set a percentage.

If you are already contributing as much as you comfortably can, or you want more investment choices, an IRA can sit alongside the TSP. Traditional and Roth IRA contribution limits and income rules also change from year to year, so confirm them at irs.gov.

What this means if you run a benefits office

Skip the headline rate. Break your numbers into three buckets: not contributing, contributing below the match threshold, and contributing at or above it. Then look at who is in each bucket by grade band, tenure, and work location. The middle bucket is often the largest, and it is the easiest to move. A short message at the right moment, such as after a promotion or an annual pay adjustment, usually does more than another all-hands seminar.

Back on that first floor, the records staff were not ignoring their retirement. They were doing what the default told them to do. Which is exactly why the default is worth a second look.