Is an IOU Legally Binding in Australia?

You lent someone money and they scribbled "IOU $2,000" on a piece of paper and signed it. Or you are about to lend, and an IOU feels less awkward than asking a friend to sign a contract. Either way, the question is the same: does that note actually count for anything?

In Australia it does count, but for less than most people hope. An IOU proves that a debt exists. It usually says nothing about when or how it has to be repaid, and that gap is where disputes start. This guide covers what an IOU is worth, where it falls short, and how to turn one into something stronger.

This article is general information, not legal advice. For a large loan or a debt that is already in dispute, consider speaking with a lawyer.

The Short Answer

What Is an IOU?

IOU stands for "I owe you". It is a short written note in which one person acknowledges owing money to another. A typical IOU has the amount, the names, a date and the borrower's signature, and nothing else.

That makes it different from a contract. A loan agreement records what both people agreed to do. An IOU records only that a debt exists.

What an IOU Proves

• That money is owed. A signed IOU is strong evidence against the common defence of "it was a gift" or "I never borrowed that".
• How much. The amount is in writing and signed by the person who owes it.
• Who owes whom. As long as both people are properly named.
• That the borrower acknowledged the debt on that date. This matters for time limits, covered below.

Together with a bank transfer showing the money leaving your account, an IOU puts you in a far better position than a purely verbal agreement.

Where an IOU Falls Short

• No repayment date. If the IOU does not say when the money is due, the two of you can end up arguing about whether it is overdue at all.
• No repayment schedule. Nothing says whether it is a lump sum or instalments, or how much each payment should be.
• No interest. If interest was discussed but not written down, it will be hard to claim.
• No consequences. Nothing covers missed payments, early repayment or what happens if the borrower's situation changes.
• Only one signature. An IOU is usually signed by the borrower alone, so it shows what they admitted, not what you both agreed.

IOU vs Promissory Note vs Loan Agreement

• IOU: an acknowledgment that a debt exists. No promise about when or how it will be repaid.
• Promissory note: a written promise by the borrower to pay a stated amount, on demand or by a stated date. Stronger than an IOU, still signed by one side only.
• Loan agreement: a contract signed by both people that sets out the amount, repayment dates, interest if any, and what happens if payments are missed. This is the document that prevents the argument in the first place.

Can You Enforce an IOU in Australia?

Yes, you can rely on one. If the borrower does not repay, the usual path is the same as for any personal debt:

• Ask for repayment in writing, with a clear date
• Send a formal letter of demand
• If that is ignored, lodge a claim in your state's small claims court or tribunal, using the IOU, bank records and messages as evidence

Our guide on what to do when a friend won't pay back a loan walks through each step.

IOUs and Time Limits

You generally have six years to start a claim for an unpaid debt in Australia, and three years in the Northern Territory. In most cases, a written acknowledgment of the debt that is signed by the borrower restarts that clock from the date it was signed.

This is one of the most useful things about an IOU. If an old loan is still unpaid and the borrower is willing to sign a fresh, dated IOU or acknowledgment, your time to claim generally starts again. The rules differ between states, so get advice if a debt is close to its time limit.

How to Make an IOU Stronger

If an IOU is all you can get, make sure it includes:

• The full legal names of both people
• The exact amount, in numbers and words
• The date the money was lent and the date the IOU was signed
• A repayment date, or a schedule of instalments
• The borrower's signature, and ideally yours as well

Once you have added a repayment date and both signatures, you have most of a loan agreement already. For anything more than a small amount, it is worth doing it properly.

Sources: Moneysmart (ASIC), Legal Aid NSW — My money, state and territory limitation of actions legislation.

Frequently Asked Questions

Is a handwritten IOU valid?

Yes. It does not need to be typed, witnessed or on a particular form. What matters is that it clearly states the amount and who owes whom, and that the borrower signed it.

Does an IOU need to be witnessed?

No. A witness is not required, though an independent witness can help if the borrower later claims they never signed it.

Is a text message saying "I owe you $500" an IOU?

It is useful evidence that the debt exists, and tribunals regularly accept messages. It may not count as a signed written acknowledgment for the purpose of restarting a time limit, so a signed note is safer.

Does an IOU expire?

The note itself does not, but your right to take legal action over the debt does. In most of Australia that is six years, and three in the Northern Territory.

Can I charge interest on an IOU?

Only if interest was agreed. If the IOU does not mention it, you will generally only be able to recover the amount stated. Our private loan repayment calculator shows what different rates and terms look like.