Is the TSP a 401(k)? Understanding Federal Retirement Accounts 

So is the TSP a 401(k)? In short: no, the TSP isn’t legally a 401(k). However, they function very similarly by giving employees a tax-advantaged way to save for retirement while potentially receiving employer contributions. 

Because of those similarities, it’s easy to confuse the TSP, a 401(k), and an Individual Retirement Account (IRA). While all three are designed to help you save for retirement, they’re different types of retirement accounts that serve different purposes. 

For example, some employees mistakenly believe that because they’re already contributing to a qualified retirement plan like the TSP or a 401(k), they can’t also contribute to an IRA. In many cases, that’s simply not true. 

Understanding how these accounts compare can help you make more informed retirement planning decisions, especially if you’ve worked or plan to work in both the Federal government and the private sector. 

Related Resource: Federal Employees and IRAs Guide > 

What Is the Thrift Savings Plan (TSP)?

The Thrift Savings Plan (TSP) is a defined contribution retirement savings and investment plan available to Federal employees. 

Like a private-sector 401(k), it allows participants to contribute a portion of each paycheck toward retirement while receiving valuable tax advantages. 

Eligible Federal Employees Retirement System (FERS) participants also receive automatic government contributions and matching contributions, which makes the TSP a key part of FERS retirement planning. 

Related resource: CSRS vs FERS – Understanding Federal Retirement Systems > 

Is the TSP Legally a 401(k)?

No. 

The TSP and a 401(k) are established under different laws and administered differently. 

However, from an employee’s perspective, they function in many of the same ways. 

Both allow you to: 

• Invest your contributions  
• Grow your retirement savings with tax advantages  
• Potentially receive employer contributions  
• Roll eligible retirement funds between qualified retirement plans  

For most retirement planning conversations, describing the TSP as “the Federal government’s version of a 401(k)” is a reasonable way to think about it. 

How the TSP and 401(k) are Similar

Tax Advantages 

Both the TSP and a 401(k) offer tax-advantaged retirement savings. 

Participants may choose between:

• Traditional (pre-tax) contributions  
• Roth (after-tax) contributions, if available

Investment earnings grow tax-deferred until withdrawn under applicable IRS rules. 

Employer Contributions 

Both plans may include employer contributions. 

For eligible FERS employees: 

• Agencies automatically contribute 1% of basic pay.
• Agencies match employee contributions up to 5%.

Private-sector 401(k) matching varies by employer and is often one factor employees consider when comparing compensation and benefits packages. The amount usually ranges between 4% and 6% of salary, and may be on a vesting schedule. 

Contribution Limits 

Both the TSP and 401(k) plans follow annual IRS contribution limits, which are put in place so that tax-advantages don’t overwhelmingly benefit higher-paid workers. 

Those limits are adjusted periodically and apply to employee retirement contributions regardless of which type of plan you participate in. 

In 2026, those limits are: 

• $24,500 for a 401(k) 
• $24,500 for a TSP 
• $7,500 for an IRA 

Different catch-up contribution limits apply for employees aged 50 and over. 

Withdrawal Rules 

Both accounts are designed for retirement savings, although having the option to withdraw funds early can be necessary during financial hardship.  

Generally, withdrawals before age 59½ may be subject to ordinary income taxes and an additional 10% early withdrawal penalty, although exceptions exist. 

It’s important to note that for both 401(k) and TSP, you typically cannot put the money back in once it’s withdrawn. 

Key Differences Between the TSP and 401(k)

Eligibility 

The biggest difference is who can participate in each type of account.  

The TSP is limited to Civilian Federal Employees and some uniformed service members. Meanwhile, private-sector employees are able to have one or more 401(k) accounts. 

If you’ve worked in both sectors throughout your career, it’s also possible to have both a TSP and one or more 401(k) accounts. 

Investment Options 

The TSP offers three different investment approaches to participants: 

• Lifecycle Funds (L Funds): automatically adjust your investment mix over time based on a target retirement date. 
• Individual Funds: which offer a mix of investments from individual TSP funds. 
• Mutual Fund Window: those who meet certain eligibility requirements and pay necessary fees can invest a portion of their savings in mutual funds. 

Meanwhile, many private-sector 401(k) plans offer a much broader selection of mutual funds and investment options, although the quality and costs vary by employer. 

Administrative Costs

One of the TSP’s biggest advantages is its low administrative expenses. 

Because of its size and structure, the TSP generally has lower fees than many private-sector 401(k) plans. 

Lower fees can help more of your investment returns stay invested and continue growing over time. 

Can I Have Both a TSP and a 401(k)? 

Yes. 

Many employees spend part of their careers in Federal service and part in the private sector, and as a result, have both a TSP and one or more 401(k) accounts. 

Having both accounts isn’t unusual, especially for employees who change careers over time. 

Can My TSP Convert to a 401(k) if I Leave the Government? 

Not automatically. 

If you leave Federal service, your TSP remains exactly what it is. However, you have several options. 

Depending on your circumstances, you may choose to: 

• Leave your money in the TSP  
• Roll funds into a Traditional IRA  
• Roll funds into a Roth IRA (tax implications may apply)  
• Roll funds into a new employer-sponsored retirement plan  
• Cash out your account (which may trigger taxes and penalties)  

Many former Federal employees choose to leave their money in the TSP because of its low fees, while others prefer consolidating retirement accounts after changing employers. 

As more employees leave Federal service before retirement eligibility, understanding these options becomes increasingly important. 

Related Resource: Leaving Federal Service? Protect Your Benefits, Coverage, and Financial Future During the Transition > 

Can I Roll My 401(k) Into My TSP?

In many cases, yes. 

The TSP accepts many eligible retirement plan rollovers. 

For example: 

• Traditional 401(k) balances can generally be rolled into a Traditional TSP balance.  
• Traditional IRAs can generally be rolled into a Traditional TSP balance.  
• Roth IRAs cannot be rolled into a Roth TSP balance.  

Because rollover rules depend on the type of retirement account and IRS regulations, it’s always a good idea to review current TSP guidance before making a transfer. 

Retirement Planning Beyond the Account 

Whether you’re saving through a TSP, a 401(k), or both, retirement planning is about more than selecting an investment account. 

Building financial confidence in retirement involves preparing ahead, consistently saving, understanding your benefits, and creating a plan that supports the lifestyle you want after your career. 

Wherever you are in your retirement planning journey, taking small steps today can make a meaningful difference in your future financial security. 

WAEPA’s free Saving for Retirement Guide offers several strategies and actionable steps for saving for retirement, regardless of where you might be in your saving journey.  

For more resources, wherever you are in your retirement planning journey, explore our free library of Federal retirement planning resources.