Last reviewed by Robert Prime, 12 October 2026. Checked that day against the Copyright, Designs and Patents Act 1988, the IPO’s guidance on ownership of copyright works, and Amazon’s KDP Terms and Conditions. This is general information, not legal advice. If real money or an existing book is at stake, have a solicitor read your agreement before you both sign.
Quick Answer: A book two people write together, where you can’t tell whose words are whose, is a joint work under UK law, and you own its copyright together. Neither of you can license it, sell rights or move it to a new publisher without the other. Amazon pays one account and leaves the split to you. Put five things in writing before you start: ownership, the money split, who runs the publishing accounts, how decisions are made, and how either of you can leave.
Table of Contents
- Who owns a co-written book in the UK
- Why one co-author can’t act alone
- How Amazon pays co-authors
- What a co-author agreement should cover
- Copy-paste co-author agreement clauses
- Tax: are you a partnership?
- Common mistakes
- Frequently asked questions
Who owns a co-written book in the UK
The Copyright, Designs and Patents Act 1988 defines a “work of joint authorship” as a work “produced by the collaboration of two or more authors in which the contribution of each author is not distinct from that of the other author or authors” (s.10).
So there are two kinds of co-written book:
| How you wrote it | What the law sees | Who owns what |
|---|---|---|
| You both drafted and rewrote the same chapters | One joint work | You own the whole copyright together |
| One of you wrote Part 1, the other Part 2, kept separate | Two works in one book | Each owns the part they wrote |
| One wrote the text, the other drew the pictures | Text and artwork are separate works | Each owns their own work |
The IPO’s guidance gives the same split: where the parts are separate, “each person would be the author of the part they created”. It also says collaborators “can agree in advance that copyright in what is to be produced should be owned by a single person or body” (IPO, ownership of copyright works). That is the job of your agreement.
For a joint work, copyright lasts 70 years from the end of the year the last of you dies (s.12(2) and (8)). Your estates will be co-owners after you, which is one more reason to write it down.
Why one co-author can’t act alone
Section 173(2) is the line that catches people out: where copyright is owned jointly, “any requirement of the licence of the copyright owner requires the licence of all of them” (s.173).
In practice, without the other co-author’s agreement, one of you cannot:
- sign an audiobook, translation or film deal;
- move the book to a new publisher or a new distributor;
- license an extract to a magazine or a course.
And if you fall out, nobody can do any of those things. A book stuck between two people who no longer speak is the most common way co-written books die.
If one of you wants to hand their share to the other, that must be done properly: an assignment of copyright “is not effective unless it is in writing signed by or on behalf of the assignor” (s.90(3)). A text message saying “it’s all yours” is not enough.
How Amazon pays co-authors
KDP lets you list more than one author: “If you have more than one author, you can list them in the Contributors section”, and you can add up to 10 contributors (KDP help: contributors). That puts both names on the product page. It does not split the money.
KDP pays royalties to the single account that published the book. Its terms say that account holder “will be solely responsible for accounting and paying any co-owners or co-administrators of any Book” (KDP Terms and Conditions, section 5.8(e), last updated 27 September 2024).
So one of you receives every penny, pays tax on it first, and must pass the other’s share on. Your agreement needs to say who holds the account, how often they pay out, and that they show the other the KDP sales report.
KDP also says that once a book is published “you won’t be able to change your book’s primary author field” (same help page). Decide whose name goes first before you press publish.
What a co-author agreement should cover
| Clause | The question it answers |
|---|---|
| Parties and the book | Who is agreeing, about which book (working title, series)? |
| Ownership | Joint copyright, or does each own their part? |
| Credit | Name order on the cover, contributor roles |
| Money | Split of royalties and of costs (editing, cover, ISBNs, ads) |
| Accounts | Who holds the KDP and other accounts; when and how they pay out |
| Decisions | Price, cover, blurb, ads: who decides, and what if you disagree |
| Other rights | Audio, translation, film: both must agree; how income is split |
| Leaving | How one of you can exit or be bought out |
| Death or incapacity | What passes to each estate and who runs the accounts |
| Sequels | Can either of you use the characters or world without the other? |
| Disputes | Talk first, then mediation, before court |
Copy-paste co-author agreement clauses
These are starting points to adapt, not a finished contract. Fill in the brackets, delete what does not apply, and both sign and date it.
Ownership
The Authors, [Name A] and [Name B], are writing a book provisionally titled "[Title]" (the Work). The Authors agree that the Work is a work of joint authorship and that the copyright in it is owned by them jointly in equal shares. Neither Author may assign, license or charge any right in the Work without the written agreement of the other.Credit
The Work will be credited on its cover, title page and all retail listings as "[Name A] and [Name B]", in that order, in every edition and format, unless both Authors agree otherwise in writing.Money and costs
All net income from the Work, in every format and territory, will be shared [50/50 / 60/40 in favour of Name A]. Agreed costs of publishing the Work (including editing, cover design, formatting, ISBNs and advertising) will be shared in the same proportions. No cost over £[amount] will be incurred without the written (including email) agreement of both Authors.Accounts and payment
[Name A] will hold the publishing accounts for the Work, including Amazon KDP. Within [30] days of the end of each calendar month in which royalties are received, [Name A] will pay [Name B] their share and send them the platform's sales report for that month. Each Author is responsible for their own tax on their share.Decisions
Price, cover, description, categories and advertising spend will be agreed by both Authors. If they cannot agree within [14] days, [Name A] will decide on price and advertising, and [Name B] will decide on cover and description. Neither Author will unreasonably withhold agreement.Exit and buy-out
Either Author may offer to sell their share of the copyright to the other at a price agreed between them or, failing agreement, set by an independent valuer both accept. Any transfer will be by a written assignment signed by the Author transferring their share. Until a transfer is signed, this agreement continues.Death or incapacity
If an Author dies or becomes unable to manage their affairs, their share of income will be paid to their estate or legal representative, and the other Author may continue to run the publishing accounts under this agreement.Sequels and spin-offs
Characters, settings and worlds created for the Work are owned jointly. Neither Author will publish a sequel, prequel or spin-off using them without the written agreement of the other.Tax: are you a partnership?
We could not find a gov.uk page that says whether two authors sharing one book are automatically a partnership, so we won’t tell you that you are. What gov.uk does say about partnerships: “you and your partner (or partners) personally share responsibility for your business”, “each partner pays tax on their share”, and a “nominated partner” registers the partnership for Self Assessment while “the other partners need to register separately” (Set up a business partnership).
If you are setting up a joint business with shared costs, ads and several books, ask an accountant whether to run it as a partnership or a company. For one book where one of you simply pays the other a share, say in your agreement that each of you handles your own tax. Our UK author tax guide covers how royalties are taxed.
Common mistakes
- Starting without anything in writing. Agreement is easy at the start and almost impossible after a falling out.
- Assuming the KDP account holder owns the book. They own the account, not the copyright.
- Splitting by word count. It invites arguments. Agree a percentage up front.
- Forgetting sequels. The characters you made together are the most valuable thing you own.
- Forgetting the estates. Copyright outlives you by 70 years.
Frequently asked questions
Do we need a solicitor for a co-author agreement?
You can draft and sign one yourselves using the clauses above. A solicitor is worth paying for when an existing book is already earning, or when audio, translation or film deals are on the table.
Can my co-author publish our book without me?
They should not. A licence of a jointly owned copyright needs all the owners (CDPA s.173). Your agreement should say who runs the accounts so this never comes up.
How does KDP split royalties between co-authors?
It does not. It pays the one account, and its terms make that account holder “solely responsible” for paying co-owners.
Can we list both names on Amazon?
Yes. Add the second author in the Contributors section. Choose the primary author carefully: it is locked after publishing.
How long does copyright last on a co-written book?
70 years from the end of the year in which the last surviving author dies.
Final thoughts
Write the agreement before chapter one. It takes an evening, and it is the cheapest insurance a co-written book can have.
If you are also hiring a cover designer, a ghostwriter or quoting other people’s work, the UK Author Legal Pack has those contracts and the permission letters. The free copyright page generator will write a copyright page with both of your names on it.
Related guides
- Ghostwriter contract UK
- ISBN vs copyright in the UK
- Sole trader or limited company for authors
- UK self-publishing legal and tax hub
— Robert publishing.co.uk
