What is self-plagiarism?
Self-plagiarism is reusing work you have already submitted or published, in whole or in part, and presenting it as new without permission or acknowledgement. It is sometimes called duplicate submission, recycling or, in research, duplicate or redundant publication. The words are yours, but the claim that the work is new is not accurate.
So yes, you can plagiarize yourself. Plagiarism is not only about taking credit for someone else’s words; it is about misrepresenting where work came from. Handing in an old essay as if you wrote it for this assignment misrepresents it, even though you are the author.
Why reusing your own work counts as plagiarism
It can feel unfair. You did the work, so why can you not use it? There are three reasons most policies give.
The assignment is meant to show new learning
A course assignment exists so you practise and demonstrate skills from that course. An essay written for a different class, or a previous year, cannot show that. Resubmitting it earns credit twice for one piece of work.
It misleads the reader
An instructor, editor or reviewer assumes that what you submit is new unless you tell them otherwise. Silent reuse breaks that assumption, in the same way that uncited copying does.
In publishing, you may not own the text any more
When a paper or article is published, the author often transfers or licenses copyright to the publisher. Reusing large parts of it elsewhere can breach that agreement, as well as the journal’s editorial policy.
Examples of self-plagiarism
Self-plagiarism ranges from obvious to borderline. These scenarios show where the line usually falls in coursework and in publishing.
| Situation | Usually self-plagiarism? |
|---|---|
| Resubmitting an essay from a previous course for a new assignment | Yes, without permission |
| Copying several paragraphs from last term’s paper into a new one | Yes, without disclosure and citation |
| Submitting the same paper to two classes in the same term | Yes, unless both instructors agree |
| Publishing the same findings in two journals as if each were original | Yes (duplicate publication) |
| Expanding a short class paper into a thesis chapter, with your supervisor’s knowledge | No, if disclosed and cited |
| Reusing your own notes, reading and ideas in a new argument | No |
Self-plagiarism is one of several forms of plagiarism. Our guide to the types of plagiarism covers the others, from direct copying to mosaic plagiarism.
When reusing your own work is allowed
Reuse is not banned outright. Many instructors are happy for you to develop an earlier idea, especially for a capstone, dissertation or portfolio. What they need is to know about it in advance. Reuse is usually acceptable when:
- your instructor or supervisor has agreed to it, ideally in writing;
- you cite your earlier work as a source, like any other;
- the new submission adds substantial new work rather than repackaging the old;
- for publications, you have followed the journal’s policy on prior publication and preprints.
To cite your own earlier work, format it like any unpublished or published source. In APA, an unpublished course paper might look like this:
Lastname, A. (2025). Title of your earlier paper [Unpublished manuscript]. Department of History, University Name.
Institutions differ on the details, so check your course handbook or academic integrity policy. If it does not mention reuse, ask.
How to ask your instructor
Keep it short and specific. Say what you wrote before, for which course, what you want to reuse and what will be new. For example: “Last term I wrote a 2,000-word paper on urban heat islands for Geography 201. I would like to build on its literature review for this project, citing it as my own earlier work, and add new fieldwork and analysis. Is that acceptable, and is there anything you would like me to do differently?”
Attach the earlier paper if you can. Keep the reply, so you have a record if a checker later flags the overlap.
Self-plagiarism in research and publishing
For researchers, self-plagiarism overlaps with several practices journals look out for. The Committee on Publication Ethics (COPE) provides guidance that many journals use when they handle these cases.
Duplicate or redundant publication
Publishing substantially the same study, data or conclusions in more than one place without cross-reference.
Salami slicing
Splitting one study into several thin papers that each report a small piece of the same data, to increase the publication count.
Text recycling
Reusing wording from your own earlier papers, most often in methods sections. Some reuse of standard method descriptions is widely tolerated when the earlier paper is cited, but policies vary between journals and fields, so check the author guidelines.
How to avoid self-plagiarism
- Treat your old work as a source. If you use an idea or passage from it, cite it the same way you would cite anyone else.
- Ask before you reuse. A short email to your instructor, before the deadline, is almost always enough. Asking after you are flagged is much harder.
- Rewrite, do not recycle. If you are returning to a topic, start a fresh draft. Your thinking has probably moved on anyway, and the new version will be better for it.
- Keep a record. Save earlier versions and note what you submitted where. It makes disclosure easy and helps if questions come up later.
- Check before you submit. Run the new draft through a plagiarism checker and look at what it matches.
How to check your work for self-plagiarism
Whether a checker catches self-plagiarism depends on what it compares against. Web-based checkers, including ours, compare your text with pages and documents that are publicly available. They will match your earlier work if it was published online, for example in a journal, a blog or a public repository. Many institutional systems also keep a private store of past submissions, which is how resubmitted coursework is usually caught.
Running your own check shows where your draft overlaps with published sources, so you can add a citation, quote properly or rewrite before you submit. With Plagiarism Checker Plus, your first check is free up to 1,000 words with no account, and a free account gives you 3,000 words a month. For institutions that want to check against their own past submissions, see Plagiarism Checker Plus for institutions.
If a report flags your own earlier work, that is not a finding of misconduct. It is a prompt to check whether the reuse was disclosed. Our guide to reading a plagiarism report explains how to judge each match.