What Is Self-Plagiarism? | Definition & How to Avoid It

Plagiarism often involves using someone else’s words or ideas without proper citation, but you can also plagiarize yourself. Self-plagiarism means reusing work that you have already published or submitted for a class. It can involve:

  • Resubmitting an entire paper
  • Copying or paraphrasing passages from your previous work
  • Recycling previously collected data
  • Separately publishing multiple articles about the same research

Self-plagiarism misleads your readers by presenting previous work as completely new and original. If you want to include any text, ideas, or data that you already submitted in a previous assignment, be sure to inform your readers by citing yourself.

To ensure your text doesn’t contain unintentional self-plagiarism, get your document checked before submission by specialized self-plagiarism software, such as our Self-Plagiarism Checker.

Examples of self-plagiarism

You may be committing self-plagiarism if you:

  • Submit an assignment from a previous academic year to a current class
  • Recycle parts of an old assignment without citing it (e.g., copy-pasting sections or paragraphs from previously submitted work)
  • Use a dataset from a previous study (published or not) without letting your reader know
  • Submit a manuscript for publication containing data, conclusions, or passages that have already been published without citing your previous publication
  • Publish multiple similar papers about the same study in different journals
Examples: Self-plagiarism
You are working on your capstone project, your last big assignment before graduation. You have chosen to write a thesis about the effects of Brexit on European commerce. You already wrote a paper about Brexit for a previous course, so you may not see any harm in reusing a section or two in your thesis. However, if you don’t cite yourself, you are committing self-plagiarism.
You have conducted research on the effects of the recent elections on policy initiatives. You submit your findings to all relevant academic journals. You may think you are broadening your chances of getting published, but in fact you are at risk of committing self-plagiarism if multiple journals opt to publish your research.
You are working on a new paper about military spending, and realize that a portion of a dataset that you used in a previously published paper would really enhance your current dataset. Since it’s your data, you don’t see any harm in adding it to your new dataset. However, if you don’t cite yourself, you are committing self-plagiarism.

Why is self-plagiarism wrong?

While self-plagiarism may not be considered as serious as plagiarizing someone else’s work, it’s still a form of academic dishonesty and can have the same consequences as other forms of plagiarism. Self-plagiarism:

  • Shows a lack of interest in producing new work
  • Can involve copyright infringement if you reuse published work
  • Means you’re not making a new and original contribution to knowledge
  • Undermines academic integrity, as you’re misrepresenting your research

It can still be legitimate to reuse your previous work in some contexts, but you need to acknowledge you’re doing so by citing yourself.

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How to cite yourself

It can be legitimate to reuse pieces of your previous work, but you need to ensure you have explicit permission from your instructor before doing so, and you must cite yourself.

You can cite yourself just like you would cite any other source. The examples below show how you could cite your own unpublished thesis or dissertation in various styles.

Example: Citing an unpublished thesis or dissertation
APA format Author last name, Initials. (Year). Title: Subtitle [Unpublished type of thesis or dissertation]. University Name. URL or DOI
APA reference entry Merkus, J. (2018). The power of reading: The effect of different reading methods on the vocabulary of multilingual children [Unpublished master’s thesis]. Radboud University.
APA in-text citation (Merkus, 2018)
APA format Author last name, First name. Title: Subtitle. Year. University Name, type of thesis or dissertation.
MLA Works Cited entry Merkus, Julia. The Power of Reading: The Effect of Different Reading Methods on the Vocabulary of Multilingual Children. Radboud University, master’s thesis.
MLA in-text citation (Merkus, 15)
Chicago bibliography entry Last name, First name. “Title: Subtitle.” Type of thesis or diss., University Name, Year.

Merkus, Julia. “The Power of Reading: The Effect of Different Reading Methods on the Vocabulary of Multilingual Children.” Master’s thesis, Radboud University, 2018.

Full note Author first name Last name, “Title: Subtitle” (type of thesis or diss., University Name, Year), Page number(s).

1. Julia Merkus, “The Power of Reading: The Effect of Different Reading Methods on the Vocabulary of Multilingual Children” (master’s thesis, Radboud University, 2018), 15.

Short note Author last name, “Shortened Title,” Page number(s).

2. Merkus, “Power of Reading,” 21.

How do educational institutions detect self-plagiarism?

In addition to plagiarism software databases, many educational institutions keep databases of submitted assignments. Sometimes, they even have access to databases at other institutions. If you hand in even a portion of an old assignment a second time, the plagiarism software will flag it as self-plagiarism.

Online plagiarism checkers not affiliated with a university don’t have access to the internal databases of educational institutions, and therefore their software cannot check your document for self-plagiarism.

In addition to our Plagiarism Checker, Scribbr also offers a Self-Plagiarism Checker. This unique tool allows you to upload your own original sources and compare them with your new assignment. It will flag any unintentional self-plagiarism, in addition to other forms of plagiarism, and helps ensure that you add the correct citations before submitting your assignment.

Scribbr’s Self-Plagiarism Checker for self-plagiarism

Online plagiarism scanners do not have access to internal university databases, and therefore cannot check your document for self-plagiarism.

Using Scribbr’s Self-Plagiarism Checker, you can upload your previous work and compare it to your current document:

  • Your thesis or dissertation
  • Your papers or essays
  • Any other published or unpublished documents

The checker will scan the texts for similarities and flag any passages where you might have self-plagiarized.

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Frequently asked questions about plagiarism

Can you plagiarize yourself?

Yes, reusing your own work without acknowledgment is considered self-plagiarism. This can range from re-submitting an entire assignment to reusing passages or data from something you’ve turned in previously without citing them.

Self-plagiarism often has the same consequences as other types of plagiarism. If you want to reuse content you wrote in the past, make sure to check your university’s policy or consult your professor.

When do I need to cite myself?

If you are reusing content or data you used in a previous assignment, make sure to cite yourself. You can cite yourself just as you would cite any other source: simply follow the directions for that source type in the citation style you are using.

Keep in mind that reusing your previous work can be considered self-plagiarism, so make sure you ask your professor or consult your university’s handbook before doing so.

Does Turnitin check for self-plagiarism?

Most institutions have an internal database of previously submitted student papers. Turnitin can check for self-plagiarism by comparing your paper against this database. If you’ve reused parts of an assignment you already submitted, it will flag any similarities as potential plagiarism.

Online plagiarism checkers don’t have access to your institution’s database, so they can’t detect self-plagiarism of unpublished work. If you’re worried about accidentally self-plagiarizing, you can use Scribbr’s Self-Plagiarism Checker to upload your unpublished documents and check them for similarities.

What happens if you plagiarize?

The consequences of plagiarism vary depending on the type of plagiarism and the context in which it occurs. For example, submitting a whole paper by someone else will have the most severe consequences, while accidental citation errors are considered less serious.

If you’re a student, then you might fail the course, be suspended or expelled, or be obligated to attend a workshop on plagiarism. It depends on whether it’s your first offense or you’ve done it before.

As an academic or professional, plagiarizing seriously damages your reputation. You might also lose your research funding or your job, and you could even face legal consequences for copyright infringement.

How can I compare two documents for plagiarism?

Most online plagiarism checkers only have access to public databases, whose software doesn’t allow you to compare two documents for plagiarism.

However, in addition to our Plagiarism Checker, Scribbr also offers an Self-Plagiarism Checker. This is an add-on tool that lets you compare your paper with unpublished or private documents. This way you can rest assured that you haven’t unintentionally plagiarized or self-plagiarized.

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Tegan George

Tegan is an American based in Amsterdam, with master's degrees in political science and education administration. While she is definitely a political scientist at heart, her experience working at universities led to a passion for making social science topics more approachable and exciting to students. A well-designed natural experiment is her favorite type of research, but she also loves qualitative methods of all varieties.