Not legal or financial advice. This is general information, not legal, financial, or tax advice. Lending, interest, and tax rules vary by jurisdiction and change over time — verify the current rules for your state or nation and consult a qualified solicitor, attorney, or financial adviser before relying on this document.
What a promissory note actually is
A promissory note is the cleanest legal expression of a debt. Stripped to essentials, it is one sentence: “I promise to pay you this much money, on these terms.” Everything else — interest, schedule, default, security — elaborates that promise. What makes it a legal instrument rather than a casual note is its unconditional and definite character: a fixed sum, a clear promise, and the borrower’s signature.
The note is one-sided in a way that distinguishes it from most contracts. Usually only the borrower (the “maker”) signs, because the note records the borrower’s promise. The lender (the “payee”) does not need to promise anything in the document; their side of the bargain — handing over the money — has already happened or happens in exchange for the note. This is why a promissory note is described as a unilateral instrument, and why it is simpler than a full loan agreement.
That simplicity is its strength. A well-drafted promissory note is, in both the US and UK, a negotiable instrument — a category of document the law treats specially because notes and bills historically functioned almost like money. In the US that status comes from Article 3 of the Uniform Commercial Code; in the UK from the Bills of Exchange Act 1882, which has governed promissory notes since the Victorian era. A note that meets the requirements of those frameworks is straightforward to enforce and, if drafted as negotiable, can even be sold or transferred to a third party.
When you need one
Lending money to family or friends. The most common everyday use. A written note turns a vague “I’ll pay you back” into a clear, enforceable agreement — and, paradoxically, protects the relationship by removing the ambiguity that breeds resentment.
Private loans between individuals. Any time one person lends another a meaningful sum, the note records the principal, the interest, and the repayment terms so there is no dispute later about what was agreed.
Business loans and shareholder loans. When an owner lends money to their own company, or one business lends to another, a promissory note documents the debt cleanly — important for the company’s accounts and for tax.
Seller financing. When the seller of a property, vehicle, or business lets the buyer pay over time, a promissory note records the buyer’s promise to pay the balance, usually secured against the asset.
Settling a debt over time. Where someone owes money and the parties agree a repayment plan, a promissory note formalises the plan into an enforceable instrument.
What it must include
For a promissory note to be valid and enforceable, it must contain:
- The parties. Full legal names and addresses of the borrower (maker) and lender (payee).
- The date. When the note is made — this fixes when the obligation begins and starts the clock for limitation purposes.
- An unconditional promise to pay. The words must promise payment without conditions. “I will pay if I can afford it” is not a promissory note.
- A definite principal sum. The exact amount, ideally in both figures and words, in the correct currency.
- The interest rate. The annual rate, whether simple or compound, and how it accrues — or an explicit statement that the loan is interest-free.
- The repayment terms. On demand, lump sum on a fixed date, or instalments — with amounts, frequency, and the final maturity date.
- Default and acceleration. What counts as default, any grace period, and whether default makes the whole balance immediately due.
- The borrower’s signature and date. And, for larger sums, a witness or notarisation, plus a guarantor’s signature if there is a guarantor.
Variants
Demand note. Payable whenever the lender asks. Maximum flexibility for the lender, maximum uncertainty for the borrower. Common in informal and shareholder loans where the parties want repayment “when needed.”
Term (lump-sum) note. The entire principal plus interest is due on a single fixed maturity date. Simple and clear; suits short bridging loans.
Instalment note. Repaid in scheduled payments over time, like most consumer loans. This is where the acceleration clause matters most: without it, a defaulting borrower can be sued only for the missed instalments, not the whole balance.
Secured vs unsecured. A secured note is backed by collateral — real estate (paired with a mortgage or deed of trust in the US, a charge in the UK) or personal property (paired with a security agreement). If the borrower defaults, the lender can take the collateral. An unsecured note relies only on the borrower’s promise; the lender’s remedy is to sue. Secured notes are far stronger for the lender but need extra documentation.
Interest-bearing vs interest-free. Most notes charge interest; some, particularly family loans, do not. An interest-free note must say so explicitly. Note the tax wrinkle: in the US, the IRS may impute interest on an interest-free loan above a threshold, using the Applicable Federal Rate, treating the forgone interest as a gift.
US vs UK framing. The substance is similar, but the governing law differs. A US note is drafted with UCC Article 3 in mind and against the relevant state’s usury cap. A UK note is drafted under the Bills of Exchange Act 1882; there is no general usury cap, but the Consumer Credit Act 1974 and unfair-relationship rules apply to consumer lending, and the Limitation Act 1980 sets a six-year enforcement window (twelve if executed as a deed).
Step-by-step
Step 1 — Identify the parties and date. Full legal names and addresses of borrower and lender, and the date the note is made.
Step 2 — State the principal. The exact amount, in figures and words, in the right currency. A definite sum is a legal requirement.
Step 3 — Set the interest. The annual rate, simple or compound, and how it accrues — or state clearly that the loan is interest-free. Check your jurisdiction’s usury cap (US) so the rate is enforceable.
Step 4 — Choose the repayment structure. Demand, lump sum, or instalments. For instalments, state the amount, frequency, number of payments, and final maturity date.
Step 5 — Add default and acceleration. Define default (usually a missed payment after a grace period) and decide whether default accelerates the whole balance. For an instalment note, include acceleration.
Step 6 — Decide on security and sign. If the note is secured, describe the collateral and prepare the accompanying security document. The borrower signs and dates; for larger sums, add a witness or notarisation, and a guarantor if there is one. Keep the original safe — enforcement depends on it.
Common mistakes
Mistake 1: A vague or conditional promise. “I’ll pay you back when I’m able” is not an unconditional promise to pay a definite sum, so it is not a valid promissory note. The promise must be unconditional and the sum definite.
Mistake 2: No interest rate stated (or an illegal one). A note silent on interest may be presumed interest-free, which the lender may not have intended. Worse, a rate above the state usury cap (US) can make the interest, or even the loan, unenforceable. State the rate and check the cap.
Mistake 3: No acceleration clause on an instalment note. Without acceleration, a borrower who stops paying can only be sued for each missed instalment as it falls due — turning one default into a series of small claims. Include acceleration.
Mistake 4: Forgetting the maturity date. A note with no clear repayment date or maturity is ambiguous about when the debt is due, which complicates both repayment and the limitation period.
Mistake 5: Letting the debt go statute-barred. Once the limitation period expires (commonly six years in the UK, three to six in US states), the court will not enforce the note. Lenders who let a friendly arrangement drift can find the debt has quietly become unenforceable.
Mistake 6: Not documenting payments. As the borrower repays, the lender should keep a running record (and update or mark the note). Disputes about how much has been repaid are common where no payment record was kept.
Worked example
Aisha lends her cousin Bilal £8,000 to help him buy a van for his new business. They want it documented properly so it does not strain the family relationship.
Promissory Note Date: 6 June 2026 Borrower (Maker): Bilal Hassan, 14 Elm Road, Leeds LS2 7QX Lender (Payee): Aisha Hassan, 22 Park View, Leeds LS6 3JN
For value received, I, Bilal Hassan, promise to pay Aisha Hassan the principal sum of eight thousand pounds (£8,000) together with simple interest at 4% per annum.
Repayment: 24 monthly instalments of £347.34, due on the 1st of each month, beginning 1 July 2026, with the final payment on 1 June 2028.
If any instalment is more than 14 days late, the entire outstanding balance becomes immediately due and payable at the Lender’s option.
This note is unsecured. Signed: ________________ (Bilal Hassan), 6 June 2026.
This note works because it has everything it needs: definite parties, a definite sum (in figures and words), a stated interest rate and type, a clear instalment schedule with a maturity date, a default trigger with a grace period, and an acceleration clause. Aisha keeps the signed original. Because the loan carries a modest interest rate rather than being interest-free, there is no question of it being treated as a gift, and because the terms are written down, neither cousin can later misremember the deal. If Bilal defaults, Aisha has a clean, enforceable instrument — and the family relationship has a clear set of rules rather than a simmering ambiguity.
Primary sources
- Cornell Legal Information Institute — Promissory Note — law.cornell.edu/wex/promissory_note — a concise statement of what a promissory note is and the essential elements US law requires.
- UCC Article 3 (Negotiable Instruments) — law.cornell.edu/ucc/3 — the US framework, adopted in every state, that makes a properly drafted promissory note a negotiable instrument.
- Bills of Exchange Act 1882 — legislation.gov.uk/ukpga/Vict/45-46/61 — the UK statute that has governed promissory notes for over a century.
For consumer loans, the UK’s Consumer Credit Act 1974 and the US Truth in Lending Act add disclosure requirements, and US state usury statutes cap interest rates. The Limitation Act 1980 (UK) and state limitation statutes (US) set the window for enforcement.
Related categories
A promissory note often accompanies a transfer documented by a bill of sale — particularly in seller-financed sales where the buyer pays over time. An LLC that lends to or borrows from its members records the debt in a note alongside its operating agreement. A landlord and tenant who agree a repayment plan for arrears might use a note alongside a rental agreement or lease agreement, and an NDA often sits beside a note in a private business deal. For the invoicing side of a business that lends or is owed money, the invoice template in the business hub handles billing.