How Do You Write a Payment Agreement Between Two Parties?

A payment agreement between two parties holds up when it names both people, describes the debt, lays out exactly when and how much gets paid, and spells out what happens if a payment is missed. The document doesn’t need legal jargon. It needs specifics: dollar amounts, dates, interest terms, and consequences, all in writing and signed before any money moves.

Name the Parties and Describe the Debt

Open with the full legal names and current addresses of both sides. If one party is a business, use its registered name rather than the owner’s personal name. Nicknames and abbreviations create problems later if the agreement ever has to be enforced.

Then describe the debt itself. State the amount owed and how it arose. “John Doe owes Jane Smith $15,000 for unpaid consulting work performed between January and March 2026” is far more useful than “John owes Jane money.” If the agreement settles or restructures an older debt, reference the original obligation and note that this document replaces it.

Build the Payment Schedule

Most disputes start in the schedule, so precision here saves the most trouble. Spell out the total repayment amount, the size of each installment, and the exact due dates. “Monthly payments of $500 due on the first business day of each month, beginning August 1, 2026, and continuing through July 1, 2029” leaves no room for argument. “Monthly payments until paid off” invites it.

For loans with interest, consider attaching an amortization schedule as an exhibit. It breaks each payment into principal and interest and shows the remaining balance after every installment. The borrower sees the debt shrink; the lender has a clean record of what’s owed on any given date. List the payment number, the interest portion, the principal portion, and the ending balance for each period.

If payments vary in size or timing, list them individually. A balloon payment at the end of the term deserves its own line so neither party can claim they didn’t see it coming.

Set the Interest Rate

If you’re charging interest, state the annual rate, whether it’s fixed or variable, and the calculation method. Simple interest charges only on the original principal balance. Compound interest charges on the principal plus previously accrued interest. The difference adds up over a multi-year repayment, and the agreement should leave no doubt which method applies.

State Usury Caps

Every state caps the interest rate you can charge on a private loan, and the limits vary widely. Some states cap private-loan rates in the single digits; others allow rates above 20%. Federal law preempts state interest-rate ceilings only for certain residential mortgage loans, so private payment agreements are fully subject to state caps.¹ Charging more than your state allows can cost the lender all the interest, trigger damages owed to the borrower, or in some states void the whole agreement. Check your state’s usury statute before setting a rate.

Zero-Interest and Below-Market Loans

Going the other direction creates a different problem. If the rate on a private loan falls below the IRS Applicable Federal Rate, the IRS treats it as a “below-market loan” and imputes interest that never actually changed hands.² The lender ends up owing tax on interest they never collected, and depending on the relationship, the forgone interest may also count as a taxable gift. Look up the current AFR before you finalize your rate; the tax section below covers the mechanics.

Late Fees, Default, and Acceleration

Spell out the penalty for late payments. A flat dollar amount or a percentage of the missed payment are both common. Keep it reasonable. Courts in many jurisdictions throw out late fees that look more like punishment than compensation. A fee of 5% of the missed installment is typical for private agreements.

Define exactly what counts as a default. Missing a single payment is the most common trigger, but you can also include the borrower filing for bankruptcy, making a false statement in the agreement, or failing to maintain required insurance on collateral. List each trigger explicitly so the borrower knows the boundaries.

An acceleration clause is what gives default consequences their teeth. It lets the lender demand the entire remaining balance immediately when the borrower defaults, instead of suing for each missed installment as it comes due. Pair it with a written notice requirement and a short cure period. Courts are more willing to enforce acceleration clauses that give the borrower a fair chance to fix the problem first.

Prepayment, Governing Law, and Dispute Resolution

State whether the borrower can pay off the debt early without penalty. Most private agreements allow it, and borrowers expect the option. If you include a prepayment penalty, describe how it’s calculated, and check that your state doesn’t restrict penalties on the type of loan you’re writing.

Include a clause identifying which state’s laws govern the agreement. This matters most when the two parties live in different states. Without a governing-law clause, a court has to decide which state’s law applies, which adds cost and uncertainty to any dispute.

Decide upfront how disagreements will be handled. The three basic options are litigation in court, binding arbitration, or mediation followed by one of the other two if mediation fails. Mediation is the least expensive and keeps control with the parties, since the mediator can only help negotiate. Arbitration is more structured and produces a binding decision, but it costs more. A stepped clause that requires mediation first and arbitration if mediation fails gives you the best of both.

Securing the Debt with Collateral

An unsecured agreement relies entirely on the borrower’s promise. If the loan is large enough to justify it, the lender can require specific property as collateral. Describe the collateral in enough detail that there’s no question what property is covered.

For personal property like a vehicle, equipment, or inventory, the lender typically files a UCC-1 financing statement with the appropriate state office. The filing puts other creditors on notice and establishes the lender’s priority. Skip the filing and another creditor who does file could end up ahead of you in line even if your loan came first. Errors in the filing, especially a misspelled legal name, can invalidate the secured interest entirely, so accuracy matters.

For real property, the lender records a mortgage or deed of trust with the county recorder’s office. Either way, the payment agreement should reference the collateral, describe what the lender can do with it on default, and note the required filings.

What Makes the Agreement Legally Enforceable

A signed document only works if it meets the basic requirements of a valid contract. These aren’t complicated, but skipping any one can make the whole thing unenforceable.

Offer and acceptance. One party proposes terms, the other agrees, and both understand what they’re agreeing to.
Consideration. Each side gives up something of value. The lender gives up the right to demand full payment immediately; the borrower commits to repay on schedule. That exchange is the consideration.
Capacity. Both parties must be legal adults of sound mind. An agreement signed by a minor or by someone who couldn’t understand what they were signing is voidable.
Legal purpose. The agreement can’t involve anything illegal. A contract to repay gambling debts, for example, may be unenforceable in states where the underlying activity is prohibited.

Put It in Writing

Most states have a version of the statute of frauds, which requires certain contracts to be in writing to be enforceable. Contracts that can’t be completed within one year generally fall under this rule, as do contracts for the sale of goods worth $500 or more. Even where the law doesn’t strictly require it, an oral payment plan is extraordinarily hard to enforce. Write it down.

Notarization

Notarization isn’t legally required in most situations, but it adds a layer of protection. A notary public verifies the identity of the signers and confirms they signed voluntarily, which makes it harder for either side to later claim the signature was forged or coerced. Notary fees for a single signature typically range from a few dollars to $25 depending on the state. For an agreement involving a significant amount, it’s cheap insurance.

Tax Rules You Can’t Ignore

The IRS pays attention to private loans, and two rules in particular trip people up: imputed interest on below-market loans, and reporting requirements for interest income.

Imputed Interest

If you lend at a rate below the IRS Applicable Federal Rate, or charge no interest at all, the IRS treats the gap between what you charged and what the AFR would have produced as “forgone interest.” That phantom interest gets taxed as if the lender actually received it.³ For gift loans between family members, the forgone interest may also count as a taxable gift from lender to borrower.²

The AFR changes monthly and depends on the loan term. For March 2026, the annual compounding rates are 3.59% for short-term loans (three years or less), 3.93% for mid-term loans (over three but not more than nine years), and 4.72% for long-term loans (over nine years).⁴ The rate that applies is the one in effect the month the loan is made, based on the loan’s full term.⁵ Current rates are published monthly on the IRS website.⁶

Two exceptions soften the blow. Loans of $10,000 or less between individuals are exempt from the imputed interest rules entirely, as long as the borrower doesn’t use the money to buy income-producing assets like stocks or rental property.² For gift loans between $10,001 and $100,000, the imputed interest taxed to the lender is capped at the borrower’s net investment income for the year. If that net investment income is $1,000 or less, it’s treated as zero.³

Reporting Interest Income

If you collect $10 or more in interest during the year, file Form 1099-INT with the IRS and send a copy to the borrower.⁷ The interest is taxable income whether you file or not, and failing to file when required can trigger penalties. The borrower should keep payment records showing how much of each payment went toward principal and how much toward interest, since the interest portion may be deductible depending on how the loan proceeds were used.

Signing, Storing, and Amending

Both parties sign and date the agreement. If one party is an entity, the signer should indicate their authority (“Jane Smith, Managing Member of XYZ LLC”). Unsigned agreements are unenforceable, and undated ones create ambiguity about when the obligations began.

Electronic signatures carry the same legal weight as handwritten ones for most agreements. Under federal law, a contract cannot be denied legal effect solely because an electronic signature was used in its formation.⁸ An e-signature can be as simple as clicking an “accept and sign” button, typing a name into a signature block, or signing on a touchscreen. What matters is that the person intended the electronic action to serve as their signature. If you use e-signatures, save the full electronic record, including timestamps and any authentication steps.

Each party gets a signed original. Store it somewhere secure and accessible. The window for filing a lawsuit on a written contract varies by state but typically runs between three and fifteen years from the date of default. Keep the agreement and all related records, including proof of every payment made and received, for at least that long. Your state attorney general’s office can confirm the deadline if you aren’t sure.

Circumstances change. If both parties agree to modify the schedule, interest rate, or any other term, put the change in writing as a formal amendment signed by both sides. An unsigned email saying “sure, you can pay less next month” won’t hold up if the relationship sours later. The amendment should reference the original agreement by date, identify the specific provision being changed, and state the new terms.

1
eCFR. Preemption of State Usury Laws
2
Office of the Law Revision Counsel. 26 USC 7872 – Treatment of Loans With Below-Market Interest Rates
3
Internal Revenue Service. Publication 550 (2025) – Investment Income and Expenses
4
Internal Revenue Service. Revenue Ruling 2026-6
5
Office of the Law Revision Counsel. 26 USC 1274 – Determination of Issue Price in the Case of Certain Debt Instruments Issued for Property
6
Internal Revenue Service. Applicable Federal Rates (AFRs) Rulings
7
Internal Revenue Service. Instructions for Forms 1099-INT and 1099-OID
8
Office of the Law Revision Counsel. 15 USC 7001 – General Rule of Validity