Retirement Plan and 401(k) Loan Promissory Notes: IRS Rules

For the IRS to treat money you take from a 401(k) as a loan rather than a taxable withdrawal, the transaction has to be backed by a written agreement that meets specific federal requirements. The 401(k) loan promissory note requirements come from Treasury regulations under Internal Revenue Code section 72(p), and they cover what the document must say, how repayment must be structured, and who has to sign. Miss any of the required elements and the entire borrowed amount becomes a deemed distribution the moment the money leaves the plan.¹

What the Written Agreement Must Contain

Treasury regulations require the loan to be evidenced by a legally enforceable agreement that specifies the loan amount, the date the funds are issued, and the full repayment schedule.¹ In practice, a compliant agreement contains:

The principal amount being borrowed
The date of disbursement
The interest rate
Identification of the collateral securing the loan (your vested account balance)
A repayment schedule showing amount, frequency, and end date
Spousal consent, if the plan requires it

The agreement does not have to be a paper document with a wet signature. It is valid as either a written paper record or an electronic record delivered through a system that meets federal electronic-delivery standards.¹ Most plan administrators now handle everything through an online portal where you accept the terms with a click, which is why the term “promissory note” is a bit dated. What matters is that the agreement is enforceable under applicable law.

If any required element is missing, the IRS classifies the entire loan as a deemed distribution. That means ordinary income tax on the full amount, plus a 10% additional tax if you are under age 59½.² On a $30,000 loan, that combination can easily cost $10,000 or more.

The Loan Amount Stated in the Agreement

The principal on the note cannot exceed the lesser of $50,000 or half your vested account balance.³ If your vested balance is $80,000, the ceiling is $40,000. If it is $120,000, the $50,000 statutory cap applies first.

There is a lookback rule that trips people up. The $50,000 cap is reduced by the highest outstanding loan balance you carried during the 12 months before the new loan, minus what you still owed on the date the new loan is issued.⁴ So if you borrowed $50,000 eight months ago and have paid it down to $20,000, the maximum new loan is $50,000 minus ($50,000 − $20,000), or $20,000.

A small-balance exception permits borrowing up to $10,000 even when that exceeds half your vested balance, though not more than the full balance. Plans are not required to include this exception, so the agreement itself will tell you whether your plan does.³ And offering loans at all is optional for plan sponsors. If your plan document does not permit them, no agreement can create one.

Interest Rate and Collateral Clauses

The agreement must state a specific interest rate. Standard industry practice is the current prime rate plus one percentage point. Interest paid on the loan is not profit for a lender; it flows back into your own account, partially replacing the investment returns your portfolio would have earned while the money was out.

The collateral clause identifies your vested account balance as security for the loan. This is not a formality. It is what gives the plan a claim against your remaining retirement assets if you default, and it is why plans that provide survivor annuity protections require spousal consent before the loan can be issued.

Repayment Terms the Agreement Must Lock In

Federal law imposes three repayment requirements, and all three must appear in the loan agreement:

A term of no more than five years from the date the loan is made, for general-purpose loans⁵
Level amortization, meaning substantially equal payments that include both principal and interest — no small payments now with a balloon later⁵
Payments no less frequent than quarterly, though most plans align them with payroll cycles so they happen biweekly or monthly⁵

An agreement missing any of these terms produces a deemed distribution the moment the loan is issued.¹

Primary Residence Loans

If the loan is used to buy your primary residence, the agreement can specify a repayment term longer than five years.⁵ Federal law does not set a maximum. Individual plan documents set the actual cap, and 10 to 30 years is a common range. Level amortization and at-least-quarterly payments still apply. This exception covers only a home purchase, not refinancing, renovations, or paying off an existing mortgage.

Military Service Suspension

If you are called to active duty, the plan can suspend repayments for the length of your service. When you return, payments resume at the same frequency and amount as before, and the repayment deadline extends by the length of your service period. A five-year loan with a one-year deployment effectively becomes a six-year loan. Interest continues to accrue during suspension, but if you provide a copy of your military orders, the rate is generally capped at 6%.⁶

Spousal Consent

If your plan provides a qualified joint and survivor annuity, your spouse has a legal interest in your account balance. Pledging that balance as collateral for a loan requires your spouse’s written consent before the loan can be issued.⁷

Consent must be given within 90 days before the loan is secured, though plans may use a 180-day window based on proposed regulations the IRS allows taxpayers to rely on.⁷ Most 401(k) plans that are not pension-style plans do not offer survivor annuities, so this requirement often does not apply. When it does, skipping the consent makes the loan agreement defective. Your plan administrator can confirm whether your plan is subject to it.

Signing and Funding

Most platforms handle the agreement through a secure online portal. You select the loan type, enter the amount, review the repayment schedule, and accept the terms electronically. Some plans still require mailed documents, and a few require notarization. If spousal consent applies, that paperwork must be completed before the agreement is finalized.

Once the administrator confirms the agreement meets all requirements, funding usually takes three to ten business days. Repayments begin on the next scheduled payroll date after disbursement, and the terms locked into the agreement govern the loan from that point on.

What Can Invalidate the Agreement Later

A properly written agreement can still fall apart after it is signed. Two situations account for most failures.

The first is a missed payment. Treasury regulations permit plans to offer a cure period running through the end of the calendar quarter following the quarter in which the payment was due.¹ A payment missed on February 15 can be cured through June 30. Miss the cure period and the outstanding balance plus accrued interest becomes a deemed distribution reported on Form 1099-R.⁸ You still owe the debt under the original agreement, and you now also owe tax on the unpaid amount.

The second is leaving your job. Separation from employment can trigger a demand for full repayment of the outstanding balance. If you cannot pay, the plan treats the unpaid amount as a distribution.³ There is a rollover option: if the unpaid balance qualifies as a plan loan offset triggered by separation, you can roll the amount into an IRA or another eligible retirement plan by your tax-filing due date for that year, including extensions.⁹ Filing for an extension pushes the deadline to October 15, giving you time to pull together the cash to complete the rollover.

1
eCFR. 26 CFR 1.72(p)-1 – Loans Treated as Distributions
2
Internal Revenue Service. Retirement Topics – Exceptions to Tax on Early Distributions
3
Internal Revenue Service. Retirement Topics – Loans
4
Office of the Law Revision Counsel. 26 USC 72 – Annuities; Certain Proceeds of Endowment and Life Insurance Contracts
5
Internal Revenue Service. Retirement Plans FAQs Regarding Loans
6
Internal Revenue Service. Retirement Plans FAQs Regarding USERRA and SSCRA
7
Internal Revenue Service. Issue Snapshot – Spousal Consent Period to Use an Accrued Benefit as Security for Loans
8
Internal Revenue Service. Fixing Common Plan Mistakes – Plan Loan Failures and Deemed Distributions
9
Internal Revenue Service. Plan Loan Offsets