TSP Loans in 2026: The Real Cost Behind the Decision

1. The two TSP loan types and how they actually work

TSP loans let active federal employees and uniformed services members borrow from their own TSP balance, repay through payroll deduction, and effectively keep the interest. The TSP offers two distinct loan products:

A few rules that apply to both types:

• Minimum loan: $1,000
• Maximum loan: $50,000 — but also constrained by the lesser of (a) 50% of your vested balance or (b) your vested balance minus your highest outstanding TSP loan balance in the past 12 months
• Minimum balance to qualify: $1,000 in your own contributions (agency contributions and their earnings don’t count toward this minimum, and they can’t be borrowed against)
• Mutual Fund Window balances are excluded from any calculation — you cannot borrow against money invested through the MFW
• Maximum two loans outstanding simultaneously: one of each type, OR two general purpose. You cannot have two residential loans at the same time.

The combined civilian + uniformed services accounts. If you have both, the limits apply to your combined balance and combined outstanding loans — not separately.

2. The interest rate explained — and what "paying yourself" really means

The TSP loan interest rate is set at the G Fund interest rate from the month prior to your loan request. This rate is fixed for the entire life of the loan — it doesn’t change as G Fund rates fluctuate.

As of May 2026, the G Fund rate is 4.50%. That means any TSP loan initiated in May 2026 carries a 4.50% interest rate, fixed for the duration. If you take a 5-year general purpose loan and the G Fund rate jumps to 7% next year, your loan stays at 4.50%. Conversely, if G Fund rates drop to 2%, your loan stays at 4.50%.

Interest goes back to your account. Every payment includes both principal and interest. The principal restores your account balance. The interest is deposited into your account as well — meaning you’re literally paying interest to yourself.

This sounds like free money. It isn’t.

Here’s what "paying yourself" actually means mechanically:

1. The TSP removes the loan amount from your invested funds (proportionally from C, S, I, F, G based on your current allocation).
2. The loan amount is essentially parked in a non-investment state for the life of the loan.
3. Each pay period, your loan payment (principal + interest) is added back to your account and invested according to your current contribution allocation.

You’re not creating new money. You’re moving money out of market exposure into a fixed-return state earning the G Fund rate, then gradually restoring it. If you would have earned more than 4.50% in C, S, or I Fund during the loan period, you’ve reduced your total return. If you would have earned less, you’ve increased it.

TSP loans don’t create returns. They convert market-exposed dollars into G-Fund-rate dollars for the duration of the loan. Whether that helps or hurts depends entirely on what the markets do while you’re repaying — and on whether you would have stayed invested anyway.

3. The double-taxation myth (and the part that is true)

The single most repeated criticism of TSP loans is that they cause "double taxation." The argument goes:

• You took your loan with pre-tax dollars (or had pre-tax dollars in your Traditional TSP).
• You repay the loan with after-tax dollars from your paycheck.
• When you eventually withdraw those dollars in retirement, you’ll pay tax on them again.
• Result: the same money gets taxed twice.

This is largely wrong on the principal. The Federal Reserve Board has published research confirming the math. Here’s why the myth doesn’t hold up:

When you take a TSP loan, the loan itself is not a taxable distribution. You don’t pay tax on the borrowed amount when it leaves your account. So when you repay with after-tax dollars and later pay tax on the eventual withdrawal, that’s just one layer of tax — the same single layer of tax you would have paid if you’d never taken the loan in the first place.

The math: if you’d never borrowed, you would have:

1. Earned $X pre-tax in your paycheck → contributed pre-tax to TSP → not taxed yet
2. Pulled $X out at retirement → taxed once at retirement

If you borrow and repay, you have:

1. Earned $X pre-tax → already contributed to TSP previously (taxed once at distribution)
2. Took a non-taxable loan of $X (didn’t pay tax)
3. Repaid with $X of after-tax dollars (already taxed on this paycheck income)
4. Pulled out the same $X at retirement → taxed once

The repayment money was always going to be after-tax money — it just happened to flow through TSP instead of being spent or saved elsewhere. The principal isn’t taxed twice.

Where the myth has a kernel of truth: the interest. Loan interest is paid with after-tax dollars (from your paycheck), goes into your TSP account, and is then taxed again at withdrawal. That portion IS effectively double-taxed.

The size of that real cost:

For a $25,000 general purpose loan, the real "double taxation" cost is roughly $654 — not a trivial amount, but not the catastrophic five-figure penalty some advisors imply. The bigger cost is almost always opportunity cost (next section), not double taxation.

4. The opportunity cost most TSP loans actually create

The substantial cost of a TSP loan is what economists call opportunity cost — the returns your borrowed money would have earned if it had stayed invested in the C, S, or I Funds (or wherever your allocation directs it).

Here’s the rough math, assuming a 5-year general purpose loan at 4.50% TSP loan rate vs. a hypothetical 10% C Fund return:

A few clarifications on these numbers:

These aren’t apples-to-apples losses — the loan is being repaid each pay period, so the amount "out of market" decreases over time. The full $25,000 only sits in non-invested status for the first few months of the loan; by year 4 of a 5-year loan, most of it is back invested. The actual opportunity cost is typically 30-50% of the gross numbers shown.

Real markets don’t deliver smooth 10% returns. During years of negative or low returns (2008, 2022, March 2026), your loan rate of 4.50% would have outperformed the market. The opportunity cost only applies when markets did well during your loan period.

The opportunity cost can be zero or even negative if you would have moved to G Fund anyway during the loan period. A federal employee who was already planning to be conservatively allocated has no opportunity cost from a TSP loan — the money was going to earn G Fund rates regardless.

The match continues during the loan. Many federal employees mistakenly believe taking a TSP loan suspends agency matching contributions. It does not. As long as you keep contributing at least 5% of basic pay per pay period during the loan repayment period, the full agency match continues unchanged. The loan and your regular contributions are separate transactions.

For more on how allocation choices interact with the math here, see G Fund vs C Fund: when each one actually wins in retirement.

5. The separation trap and the QPLO rule that saves you

This is the rule most federal employees don’t know about until it’s too late: an outstanding TSP loan does not disappear when you separate from federal service.

When you leave federal service (retirement, resignation, RIF, termination), you must repay your outstanding loan in full within 90 days of the date your agency reports your separation. If you don’t:

• The unpaid balance is declared a distribution
• The distribution is added to your taxable income for the year
• If you’re under age 59½, you face an additional 10% early withdrawal penalty
• For a $30,000 outstanding loan balance at separation, that can mean $7,000-$15,000 in unexpected federal tax — on top of state tax — payable when you file the following April

The QPLO rule (Qualified Plan Loan Offset). Under the Tax Cuts and Jobs Act, if your loan is foreclosed due to separation from employment, you have until your tax filing deadline including extensions to roll the foreclosed amount into an IRA or eligible retirement plan. This replaced the old 60-day rollover window and is dramatically more workable.

The mechanic: if you separate in 2026 with a $30,000 outstanding loan balance and it gets foreclosed, you can use personal funds (savings, brokerage, line of credit) to deposit $30,000 into an IRA by the 2026 tax filing deadline (typically April 15, 2027, or October 15, 2027 with extension). That deposit replaces the foreclosed amount and eliminates the tax. You’re not rolling the same dollars; you’re using fresh money to neutralize the tax event.

Other separation realities:

• You cannot roll over an active outstanding TSP loan to an IRA. The loan must be paid off or foreclosed first.
• Payroll deductions stop automatically at separation. After that, you have until the loan’s original maturity date to make direct payments by check or direct debit. If you stop paying, the TSP forecloses.
• A foreclosed loan that becomes a taxable distribution permanently reduces your TSP account. You cannot make up the contribution — the cap on annual elective deferrals still applies. The compound growth you’d have earned on that money is permanently lost.

For more on the broader landscape of leaving federal service with TSP balances, see TSP withdrawal options in 2026.

6. Default mechanics: what happens if you can’t repay

A TSP loan defaults in two specific scenarios while you’re still employed:

1. You miss enough payments that the TSP declares a deemed distribution. TSP allows a grace period — typically up to one missed payment can be made up — but persistent missed payments trigger foreclosure.
2. The loan reaches its maximum term without being fully repaid. General purpose loans must be paid off within 60 months; residential within 180 months. Hitting the maximum date with a balance still outstanding triggers automatic foreclosure.

When foreclosure happens to an active employee (not at separation):

• The outstanding balance becomes a deemed distribution — Form 1099-R code L
• You owe federal income tax on the entire outstanding balance at your marginal rate
• If under 59½, you owe an additional 10% early withdrawal penalty
• The deemed distribution is treated as a withdrawal but doesn’t include the QPLO rollover option (that’s only for severance-related foreclosure)
• You cannot apply for another TSP loan for 12 months following the deemed distribution
• The foreclosed balance permanently reduces your TSP account — you cannot contribute to make it up

The chart shows what defaulting on a $25,000 outstanding TSP loan costs a federal employee under 59½. Even at the lowest federal bracket (12%), the combined tax + penalty exceeds $5,500. At higher brackets, the bill quickly approaches half of the loan amount — and that’s before state taxes, which can add another $500-$2,500 depending on residence.

7. When a TSP loan actually makes sense

After all those caveats, there are legitimate situations where a TSP loan is genuinely the best option:

High-interest debt consolidation. If you have $15,000 in credit card debt at 22% APR, replacing it with a $15,000 TSP loan at 4.50% is mathematically a slam-dunk — provided you stop using the credit cards. You’re trading 22% guaranteed cost for 4.50% guaranteed cost. The opportunity cost question matters less when the alternative is paying 17.5 percentage points more in interest to a credit card company.

Bridge financing for a home purchase. A residential TSP loan can cover a down payment, closing costs, or a gap between selling and buying. The 15-year repayment term keeps payments manageable, and the interest rate is typically far below private mortgage rates. The trade-off: lower TSP returns during the repayment period in exchange for not paying PMI or carrying a higher mortgage rate.

Avoiding emergency hardship withdrawals. A hardship withdrawal triggers the 10% early withdrawal penalty if you’re under 59½, plus income tax, plus you cannot contribute for 6 months following the withdrawal. A TSP loan avoids all three problems while still giving you access to the money. For a federal employee facing an unexpected $20,000 expense, the loan is structurally better than a hardship withdrawal in nearly every case.

Time-sensitive opportunities with high expected return. Investing in a small business, education that produces verifiable ROI, or other opportunities where the after-tax return clearly exceeds the loan’s opportunity cost. This is the rarest legitimate use because the bar is high — most "opportunities" don’t deliver guaranteed positive returns.

Job security is high and the loan term is short. A federal employee with strong job security taking a 2-year general purpose loan has limited exposure to the separation trap. The shorter the term and the more secure the employment, the smaller the risk that something forces premature foreclosure.

8. The alternatives most federal employees overlook

Before taking a TSP loan, the math usually works out better with one of these alternatives:

0% APR credit card balance transfer. For consolidating existing credit card debt, a 0% APR balance transfer for 15-21 months can eliminate interest entirely during the payoff window. The transfer fee (typically 3-5%) is one-time and lower than 18 months of TSP loan interest. The catch: you have to qualify for the credit limit, and you have to be disciplined enough to pay it off before the promotional rate expires.

Home equity line of credit (HELOC). For homeowners with equity, a HELOC at current rates (typically 7-9% in May 2026) is more expensive than a TSP loan but has better separation flexibility — your HELOC doesn’t accelerate if you leave federal service. The tax deduction on home equity interest may apply if the funds are used for home improvement.

Personal line of credit at a credit union. Many federal credit unions (NFCU, Penfed, etc.) offer personal loans at rates competitive with TSP loans, sometimes lower. No effect on retirement balance, no opportunity cost, no separation trap. A federal employee who qualifies for a 6% personal loan at NFCU is usually better off than taking a 4.50% TSP loan once opportunity cost and tax friction are included.

Emergency fund. If you don’t have 3-6 months of expenses in liquid savings, the most reliable financial move is building one — not borrowing. The lack of an emergency fund is what creates the "emergency" need for a TSP loan in the first place. The remedy is structural.

Cash-out refinance. For homeowners with substantial equity, a cash-out refinance can be more efficient than a TSP residential loan — especially when mortgage rates are favorable. The transaction costs are higher (closing costs typically $3,000-$8,000), but the longer amortization period and tax deductibility of mortgage interest can make the math work.

For more on the working-years borrowing and benefits coordination that determines when a TSP loan vs. a private alternative makes sense, Federal Warrior covers federal employee benefits and credit union options ↗.