The retirement spending gap worksheet finds the yearly gap that Thrift Savings Plan (TSP) savings must supply after the Federal Employees Retirement System (FERS) annuity, the FERS Supplement, Social Security and any other income. It then divides the stable assets set aside for spending by that gap to show how many years of spending they could cover. It runs the calculation twice: once while the FERS Supplement is paid, which is before age 62, and once after the Supplement ends and Social Security is counted.
Enter annual dollar amounts below. Nothing you enter is saved, stored or shared. Scroll below for more instructions on how the worksheet works.
Retirement spending gap worksheet
This worksheet estimates the spending gap, the amount Thrift Savings Plan (TSP) savings must supply after guaranteed income, and how many years of that gap could be met from stable assets. Enter annual dollar amounts. Nothing you enter is saved, stored or shared.
The calculation holds amounts flat. It ignores taxes, inflation, interest on the stable assets, annuity cost-of-living adjustments and any change in spending. Social Security is counted in the second period only, because the Supplement ends at 62 and Social Security timing varies by person.
Lifecycle (L) Fund glide path reference
Target allocations from the TSP's Lifecycle Funds page as of October 2026. The TSP adjusts these each quarter, so check tsp.gov for current figures.
| L Fund | Mix (G / F / C / S / I) |
|---|---|
| L Income | 66%15%10% 66.37% / 5.38% / 14.69% / 3.67% / 9.89% |
| L 2030 | 42%27%7%18% 41.73% / 5.77% / 27.30% / 6.82% / 18.38% |
| L 2035 | 28%6%34%9%23% 27.89% / 6.17% / 34.29% / 8.57% / 23.08% |
| L 2040 | 22%7%37%9%25% 21.60% / 6.65% / 37.31% / 9.33% / 25.11% |
Same returns, different order
Hypothetical retiree starting with $500,000 and withdrawing $25,000 at the start of each year. Both paths use annual returns of minus 20, plus 10 and plus 10 percent. This is an illustration, not a TSP figure or a forecast.
| Year-end balance | Loss first | Loss last |
|---|---|---|
| Year 1 | $380,000 | $522,500 |
| Year 2 | $390,500 | $547,250 |
| Year 3 | $402,050 | $417,800 |
Educational use only. This is not investment, tax, legal or financial advice and does not recommend any allocation or transaction. Confirm TSP and FERS rules at tsp.gov and opm.gov.
How the retirement spending gap worksheet works
The worksheet uses three steps, and each one is simple arithmetic.
- Guaranteed and other income is added up: the FERS annuity, the Supplement or Social Security (depending on the period) and any other income.
- That total is subtracted from annual spending. The result is the yearly gap, the amount the TSP would have to supply.
- Stable assets are divided by the yearly gap. The result is the number of years of that gap the stable assets could cover.
The two results differ because the income differs. The FERS Supplement is generally payable only until age 62, so the first period counts the Supplement and leaves out Social Security. The second period counts Social Security and leaves out the Supplement. Social Security timing varies by person, so the worksheet asks for the annual amount at the age it is expected to start.
Worked example
The example below is hypothetical. It uses round numbers to show how the two results are calculated, and it is not a forecast or a recommendation.
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| Item | While the Supplement is paid | After the Supplement ends |
|---|---|---|
| Annual spending | $90,000 | $90,000 |
| FERS annuity | $30,000 | $30,000 |
| FERS Supplement | $15,000 | $0 |
| Social Security | $0 | $24,000 |
| Other income | $0 | $0 |
| Total income | $45,000 | $54,000 |
| Yearly gap the TSP must supply | $45,000 | $36,000 |
| Stable assets | $120,000 | $120,000 |
| Years of the gap covered | 2.7 years | 3.3 years |
In this example, income covers 50 percent of spending in the first period and 60 percent in the second. The result says how long stable assets could cover the gap with no other changes. It does not say whether that is enough, because that depends on the retirement date, other assets and personal circumstances.
What counts as stable assets
Stable assets are balances that are set aside for spending and are not expected to swing widely in value. Many people include cash and the G Fund in this group. The TSP describes the G Fund as having no risk of loss of principal and very little volatility of earnings. The worksheet leaves the definition to the reader: whatever is entered in the stable assets box is what gets divided.
Stable does not mean growing. Stable balances may not keep pace with the cost of living over a long retirement, which is one reason the worksheet shows years covered and not a verdict. Historical fund results are available on the TSP returns page, and past results do not predict future ones.
What the worksheet leaves out
- Taxes. All amounts are treated as pre-tax dollars per year.
- Inflation. Spending and income are held flat.
- Interest or growth on stable assets.
- Cost-of-living adjustments to the FERS annuity.
- Changes in spending over time, such as one-time costs or health care changes.
- Withdrawals from other assets, including the rest of the TSP. See the overview of TSP withdrawal options for how withdrawals work.
Where the figures and rules come from
The worksheet applies rules published by government agencies. The page content was last checked on November 4, 2026.
- The FERS basic annuity formula and eligibility: the Office of Personnel Management (OPM) pages on FERS computation and FERS information.
- The FERS Supplement: OPM’s FERS pages. The Supplement is generally payable until age 62, is based on the estimated Social Security benefit at 62 multiplied by FERS service divided by 40, and is not increased by cost-of-living adjustments.
- Social Security claiming ages: the Social Security Administration (SSA) page on benefit reductions by age. For people born in 1960 or later, full retirement age is 67, and claiming at 62 reduces the monthly benefit to 70 percent of the full amount. For the claiming decision itself, see this guide to when to take Social Security.
- TSP fund information and Lifecycle (L) Fund allocations: the TSP’s Lifecycle Funds page. The allocations shown in the worksheet are as of October 2026, and the TSP adjusts them quarterly.
Common questions
What is the FERS Supplement?
The FERS Supplement, formally the Retiree Annuity Supplement, is a payment for eligible retirees that approximates the Social Security benefit earned during federal service. It is generally payable until age 62 and is subject to an earnings test if the retiree works after leaving federal service. OPM publishes the current rules.
Does the worksheet tell me how to invest?
No. It does not recommend an allocation, a fund or a transaction. It shows how much of spending guaranteed income covers and how many years of the remaining gap a given amount of stable assets could meet. What to do with the result is a personal decision.
Why are there two results?
The Supplement ends at age 62, and Social Security is counted separately because it begins at different ages for different people. Showing both periods lets the reader see how the gap changes when the Supplement stops and Social Security starts.
Is my information saved?
No. Nothing you enter is saved, stored or shared. The calculation runs in the browser, and clearing the form removes the numbers.
How often are the Lifecycle Fund allocations updated?
The TSP adjusts the allocations of the L Funds every quarter. The table in the worksheet shows the figures as of October 2026 and is updated periodically, so the current numbers should always be confirmed on tsp.gov.
Related reading
For the thinking behind the worksheet, see Questions to ask about your TSP when markets send mixed signals, which covers sequence-of-returns risk, the roles of the TSP funds and how the pension changes the amount of risk the TSP has to carry.
DISCLAIMER: This worksheet is provided for general educational purposes only. It is not investment, tax, legal or financial advice, and it does not recommend buying, selling or reallocating any investment. Results depend entirely on the numbers entered and on the simplifying assumptions described above. Readers should confirm current rules on tsp.gov, opm.gov and ssa.gov and consider consulting a qualified professional about their own situation.