TSP Contribution Calculator

Determine your optimal Thrift Savings Plan (TSP) contribution to maximize your government match and see the exact impact on your take-home pay. This calculator compares your current contribution rate to a proposed new rate, showing you precisely how much more you can save for retirement and how it affects your paycheck. It's designed specifically for federal employees under the Federal Employees Retirement System (FERS) and military members in the Blended Retirement System (BRS).

This tool is essential for any federal employee looking to optimize their retirement savings. Whether you're just starting your career or are a seasoned veteran, understanding your TSP is critical. Use this alongside other tools like the main retirement calculator or the FERS pension calculator to build a complete picture of your financial future. If you're comparing the TSP to private-sector plans, our 401(k) calculator is a useful reference.

The results provide a clear "Match Optimization" score, showing what percentage of the available government match you are capturing. You'll also see summary cards detailing your annual contribution, the per-paycheck impact, and the total annual match. A bar chart visually compares your take-home pay at current and proposed rates, and a detailed table breaks down the match formula at every contribution level, pinpointing the 5% sweet spot.

Begin by entering your financial details in the "Salary & Contribution" section. Provide your gross annual salary, your current TSP contribution rate as a percentage of your pay, and the new rate you are considering. Also, enter the number of pay periods you have per year, which is typically 26 for federal civilian employees paid biweekly.

Next, move to the "Tax Rates" section. Input your marginal federal tax bracket and your state income tax rate. These numbers are crucial for accurately calculating the change in your take-home pay, as traditional TSP contributions reduce your taxable income.

For a more detailed analysis, open the "Advanced Settings." Here you can specify your service type (FERS or BRS, though the match formula is identical), indicate if you are eligible for catch-up contributions (age 50 or over), and enter the percentage of your contribution you direct to the Roth TSP. The Roth portion is important because it's an after-tax contribution and won't lower your current taxable income.

Once all your information is entered, click the "Calculate" button to see a full breakdown of your results, including your match optimization score, paycheck impact, and a detailed comparison chart.

Annual Salary

This is your gross annual base pay before any deductions for taxes, insurance, or retirement contributions. The calculator uses this figure as the foundation for calculating both your personal contributions and the government's matching contributions.

Current & Proposed Contribution Rate

Your contribution rate is the percentage of your base pay you elect to save in your TSP account each pay period. Enter your current rate and a new "proposed" rate to compare them. This comparison is the core function of the calculator, showing you the financial trade-offs of saving more or less for retirement. See how much you should save for retirement each month for general guidance.

Pay Periods Per Year

This is the number of paychecks you receive in a year. For most federal civilian employees, this is 26 (biweekly). For military members or others on a different schedule, it might be 12 (monthly) or 24 (semi-monthly). This input allows the calculator to accurately determine the per-paycheck impact of changing your contribution rate.

Federal & State Tax Rates

Enter your marginal tax rates—the rate you pay on your next dollar of income. Traditional (non-Roth) TSP contributions are pre-tax, meaning they lower your taxable income. The calculator uses these tax rates to show you the true, after-tax cost of increasing your contribution. For example, contributing an extra $100 might only reduce your take-home pay by $75, depending on your tax bracket.

Service Type

This allows you to select between FERS (most federal civilian employees) and BRS (military members who opted in or joined after 2018). While these are very different retirement systems overall, they share the exact same TSP matching formula. The FERS pension calculator can help you plan the pension component of your FERS benefits.

Catch-Up Eligible (Age 50+)

If you are age 50 or older, you are eligible to make additional "catch-up" contributions above the standard elective deferral limit. For 2026, this allows you to contribute an extra $7,500. Select "Yes" if this applies to you, and the calculator will use the higher contribution limit.

Roth TSP Portion

This is the percentage of your total contribution that you direct to the Roth TSP. Roth contributions are made with after-tax money, meaning they don't lower your current taxable income. In exchange, qualified withdrawals in retirement are tax-free. For a deeper dive, see our comparison of Roth vs. Traditional IRAs, as the principles are similar.

This calculator models the financial impact of changing your TSP contribution rate by performing a series of calculations based on your inputs.

First, it calculates your annual employee contribution for both your current and proposed rates, ensuring the amount does not exceed the 2026 IRS elective deferral limit of $23,500 (or $31,000 if you are catch-up eligible).

Next, it applies the TSP matching formula to determine the government's contribution. It calculates the 1% automatic contribution and the additional matching funds based on your contribution rate. This is done for both your current and proposed scenarios.

Then, the calculator determines the impact on your paycheck. It calculates your gross pay per pay period and subtracts any pre-tax (Traditional) TSP contributions to find your taxable income. It applies your federal and state tax rates to this taxable income to estimate taxes owed. Finally, it subtracts taxes and your total TSP contribution (both Traditional and Roth) from your gross pay to arrive at your estimated take-home pay.

The difference between the take-home pay in the current and proposed scenarios is the "Paycheck Impact." The calculator also computes your "Match Optimization Score" by comparing the match you receive at your proposed rate to the maximum possible match.

The calculations are performed step-by-step to determine annual savings and paycheck impact.

TSP Match Formula (FERS & BRS)

The government match is calculated based on your contribution rate relative to your annual salary.

automatic_match = annual_salary * 0.01

dollar_for_dollar_match = annual_salary * min(contribution_rate, 0.03)

fifty_cent_match = annual_salary * max(0, min(contribution_rate - 0.03, 0.02)) * 0.5

total_annual_match = automatic_match + dollar_for_dollar_match + fifty_cent_match

To receive the maximum match, you must contribute at least 5% of your salary. This results in a total government contribution of 5% (1% automatic + 4% matching).

Annual Contribution

Your personal contribution is calculated and then capped at the annual IRS limit.

elective_limit = 23500 (or 31000 if catch-up eligible)

annual_contribution = min(annual_salary * contribution_rate, elective_limit)

Paycheck Impact Formula

The calculator determines the change in your take-home pay by analyzing taxes.

gross_per_paycheck = annual_salary / pay_periods

contribution_per_paycheck = annual_contribution / pay_periods

roth_portion_per_paycheck = contribution_per_paycheck * (roth_portion / 100)

pre_tax_portion_per_paycheck = contribution_per_paycheck - roth_portion_per_paycheck

taxable_income_per_paycheck = gross_per_paycheck - pre_tax_portion_per_paycheck

estimated_taxes = taxable_income_per_paycheck * (federal_tax_rate + state_tax_rate) / 100

take_home_pay = gross_per_paycheck - estimated_taxes - contribution_per_paycheck

The "Paycheck Impact" is the difference between the take_home_pay calculated for the proposed rate and the current rate.

The Thrift Savings Plan match is one of the most valuable parts of the federal benefits package. For both FERS and BRS members, it's structured to encourage saving at least 5% of your salary. If you contribute less than 5%, you are forfeiting part of your compensation.

Here is the breakdown:

1. Agency/Service Automatic (1%) Contribution: The government automatically contributes 1% of your basic pay to your TSP account. You receive this even if you contribute nothing.
2. Agency/Service Matching Contributions: The government then matches your own contributions on top of the automatic 1%.
   • The first 3% you contribute is matched dollar-for-dollar (a 100% match).
   • The next 2% you contribute is matched at 50 cents on the dollar (a 50% match).

To get the full match, you must contribute 5% of your pay. When you do, the total government contribution is 5%: the 1% automatic contribution plus 4% in matching contributions. This means for every dollar you contribute up to 5% of your salary, the government puts in another dollar. It's an instant 100% return on your investment and the most important first step in TSP investing. Use the TSP match calculator for a focused look at this benefit.

For 2026, the IRS sets specific limits on how much you can contribute to your TSP account. These limits are the same as those for 401(k) and 403(b) plans.

• Elective Deferral Limit: You can contribute up to $23,500 from your own pay. This limit applies to the combined total of your Traditional and Roth contributions.
• Catch-Up Contribution Limit: If you are age 50 or older during the calendar year, you can contribute an additional $7,500. This brings your total possible employee contribution to $31,000.
• Annual Additions Limit: The total amount of contributions to your account in a year—including your contributions, agency/service matching contributions, and the 1% automatic contribution—cannot exceed $70,000. It is rare for most federal employees to approach this limit, but it's important to be aware of.

Exceeding the elective deferral or catch-up limits can result in complicated tax consequences. The federal payroll system is designed to automatically stop your contributions once you hit the limit for the year.

The TSP offers two types of contributions: Traditional and Roth. Choosing between them depends on your current financial situation and what you expect your tax situation to be in retirement.

Traditional TSP:

• How it works: Contributions are made with pre-tax dollars. This reduces your current adjusted gross income (AGI), lowering your income tax bill for the year.
• In retirement: Your contributions and all their earnings are taxed as ordinary income when you withdraw them.
• Who it's good for: Federal employees who are in a higher tax bracket now than they expect to be in retirement. The upfront tax deduction is more valuable if your current tax rate is high.

Roth TSP:

• How it works: Contributions are made with after-tax dollars. You don't get a tax deduction in the present.
• In retirement: Your contributions and all their earnings can be withdrawn completely tax-free, provided you are at least 59½ and have had the Roth account for five years.
• Who it's good for: Those who believe their tax rate will be higher in retirement, younger employees with many years of tax-free growth ahead, or anyone who values tax diversification and the certainty of tax-free income later.

You don't have to choose just one. The TSP allows you to split your contributions between Traditional and Roth in any proportion you like. This strategy provides tax diversification, giving you flexibility in retirement to manage your taxable income. Use our Roth 401(k) calculator to model the long-term impact of this choice.

• Match Optimization Score: This gauge shows you what percentage of the maximum possible government match you are capturing with your proposed contribution rate. A score of 100 means you are getting the full match. Anything less indicates you are leaving free money on the table.
• Summary Cards: These four cards give you the most important numbers at a glance. They show your annual contribution and match at both your current and proposed rates, and most importantly, the exact dollar impact the change will have on each paycheck.
• Take-Home Pay Comparison: This bar chart provides a powerful visual of how increasing your savings affects your paycheck, monthly income, and annual take-home pay. It often reveals that the actual reduction in take-home pay is less than the contribution increase, thanks to tax savings.
• TSP Match Optimization Table: This table is your guide to maximizing the match. It shows, step-by-step, how much in government matching funds you receive at each 1% contribution interval from 0% to 10%. It clearly highlights the 5% level where the match is maxed out.
• Insights Panel: This section provides dynamic, plain-English feedback based on your specific inputs. It will confirm if you're capturing the full match, explain the paycheck impact, or issue a warning if you're falling short of the 5% threshold.

If the calculator shows you're not on track, here are the most effective steps you can take:

1. Contribute at Least 5%: This is the single most important action. If you are contributing less than 5%, you are turning down a 100% return on your money. Adjust your proposed rate to 5% in the calculator to see the impact.
2. Increase Contributions Annually: Make it a habit to increase your contribution rate by 1% each year, perhaps when you receive a pay raise. Small, regular increases are easier to absorb into your budget and can lead to massive growth over a career.
3. Maximize Catch-Up Contributions: If you are age 50 or over, take full advantage of the catch-up contribution provision. This is a powerful way to supercharge your savings as you approach retirement.
4. Balance Traditional and Roth: Use the "Roth TSP Portion" input to see how directing funds to the Roth TSP affects your paycheck. While it reduces take-home pay more than a Traditional contribution, it buys you valuable tax-free income in the future. Finding the right balance can optimize your tax-efficient withdrawal strategy.

1. Not contributing 5%: This is the most common and costly mistake. It is equivalent to refusing a portion of your salary.
2. Setting it and forgetting it: Many employees set their contribution rate when they are hired and never adjust it. Your savings rate should grow as your salary does.
3. Stopping contributions after hitting the limit: If you contribute a very high percentage early in the year and hit the $23,500 limit before year-end, your contributions will stop. If they stop, your matching contributions will also stop. It's better to spread your contributions over the entire year to ensure you get the full match.
4. Ignoring the Roth option: Failing to consider the Roth TSP, especially early in your career when you are in a lower tax bracket, can be a missed opportunity for a lifetime of tax-free growth.
5. Taking a TSP loan unnecessarily: While available, a TSP loan has opportunity costs because the money is not invested and growing. It should be considered carefully against other borrowing options.