A promissory note, in plain words

In one line. A promissory note is a one-sided paper in which one person promises to pay another a stated sum on stated terms, and its defining quality is how little else it contains.

Most contracts are conversations. Two sides, obligations running both ways, and a document that spends its length on what each of them owes the other.

A note is not that shape. Only one side promises anything. The other side simply holds the paper.

What the note says

A promissory note is short, and nearly all of it is the promise.

Who promises. The maker — the person or company that will pay.

Who is owed. The payee, sometimes described so that whoever holds the note can claim under it.

How much. The principal, in figures and often in words.

When. A date, a series of dates, or on demand — meaning whenever the holder asks for it.

Interest, if any. A rate, how it accrues, and whether it changes if payment is late.

How. The method and the place of payment.

Signed by. The maker, and the maker alone. That single signature is the structural fact about the document.

Some notes add a little more: what counts as default, whether the whole balance falls due at once if an instalment is missed, whether the note can be prepaid without penalty. Even with all of that, a note is commonly a page.

How is it different from a loan agreement?

A loan agreement is a contract between a lender and a borrower, and both sides appear in it.

The lender agrees to advance the money, sometimes in stages and sometimes subject to conditions. The borrower agrees to repay, and also to a list of other things: what the money may be used for, what information must be provided, what the borrower will not do while the loan is outstanding, what security is given, what happens on default and how the lender enforces it. Both sign.

A note contains the borrower's half and stops. That is why the two documents often appear together rather than as alternatives: a loan agreement sets out the arrangement, and a note evidences the debt in a form that stands on its own and can be passed on. A personal loan agreement between family or friends is frequently the one place a note appears with no agreement above it, because the arrangement is simple enough that the promise is the whole of it.

What it leaves out

Almost everything a full agreement would carry.

There are usually no covenants — no promises about how the money is used or what the maker will do meanwhile. There is often no security, so the note is a promise rather than a claim on any particular thing, unless a separate document says otherwise. There is rarely any machinery for renegotiation. And there is frequently no detail about enforcement beyond the fact of the debt.

The governing law line is the one piece of machinery worth checking, because it is sometimes missing altogether on a short note. It says which body of law reads the words if anyone ever has to, and that clause is its own subject.

The brevity is the point rather than an oversight. A note is built to be simple, transferable and easy to prove: here is a signed promise to pay a stated sum, and it either was paid or it was not.

Where notes turn up

Between people, when someone lends a relative money for a deposit and both of them want it written down rather than remembered.

In business lending, sitting underneath a longer facility agreement as the instrument that evidences each drawing.

In company financing, where a note is used to record money advanced before an equity round settles the price.

And in the sale of a business or an asset, where part of the price is left outstanding and recorded as a note payable over time.

The word people reach for instead is an IOU, and the difference between the two is precision rather than category. A note written on a napkin naming the maker, the payee, the sum, the date and the signature is doing the same job as one printed on headed paper. A scribbled acknowledgement that money is owed, with no sum, no date and no promise to pay, is a record of a conversation. What separates them is how many of the parts above made it onto the page.

Whether a note is the right instrument for money you are lending or borrowing depends on the amount, the relationship, local law and what happens if it goes wrong. Ask a lawyer if the sum matters to you.

At the door. contracts.io makes paper, not legal advice. Describe the arrangement in one sentence and read back a promissory note, a loan agreement or a personal loan agreement in plain language, with the governing law named from the full list — England and Wales, New York, Ireland and the rest. The parts a contract usually names is a good checklist for reading whichever one you end up with.