How to Avoid Plagiarism: Types, Self-Plagiarism, Consequences
Reviewed by Prof. Dr. Alexander Holtermann · Updated 16 October 2026 · 5 min read
Cite every idea, quote, and data point you take from others, paraphrase properly, never reuse graded work without permission, and track your sources.
Key takeaways
- Plagiarism means presenting someone else’s words, ideas, data, or work as your own, with or without intent.
- Self-plagiarism (reusing your own previously submitted work without permission) counts as academic misconduct at most universities.
- Contract cheating (paying someone to write your work) is the most serious form; in England, offering such services has been a criminal offense since 2022.
- A similarity score from a plagiarism checker is not a plagiarism verdict: properly cited quotes also match, and there is no universal “safe” percentage.
- Consequences range from a lowered grade or resubmission to failing the course, suspension, expulsion, or revocation of a degree.
What counts as plagiarism?
Plagiarism is using another person’s work without proper acknowledgment. “Work” is broad: words, ideas, arguments, data, images, code, music, and structure. It does not matter whether the source is a book, a website, a classmate’s essay, a lecture slide, or a text generated by an AI tool. What matters is that the reader cannot tell which parts are yours.
Universities in the US and UK treat plagiarism as a breach of academic integrity. In the US, many colleges have honor codes that students sign on admission; in the UK, it falls under academic misconduct regulations. Intent can affect the penalty, but accidental plagiarism is still plagiarism.
One rule beats every guide on the internet, including this one: your own university’s or department’s style guide, handbook, or assignment brief always takes precedence. If it differs from what you read here, follow it. You can upload that handbook to Professor Digital, and everything (outline, citations, checks) is tailored to it.
Types of plagiarism
Knowing the types helps you recognize risks in your own writing, especially the less obvious ones.
| Type | What it is | Severity |
|---|---|---|
| Direct (verbatim) | Copying text word for word without quotation marks and citation | High |
| Mosaic / patchwriting | Mixing copied phrases with your own words or swapping synonyms | High |
| Paraphrasing without citation | Rewording an idea correctly but not citing the source | Medium to high |
| Self-plagiarism | Resubmitting your own earlier work, or parts of it, without permission | Medium |
| Citation errors | Wrong or missing page numbers, citing a source you did not read | Low to medium |
| Collusion | Unauthorized collaboration on individual work | High |
| Contract cheating / ghostwriting | Submitting work written by someone else (paid or not) | Very high |
| Undisclosed AI-generated text | Submitting AI output as your own where not permitted or not disclosed | High (depends on policy) |
Self-plagiarism: can you reuse your own work?
Many students are surprised that reusing their own work can be misconduct. The logic: each assignment should be assessed as new work, and you cannot get credit twice for the same effort. Resubmitting an essay from another course, or copying paragraphs from your earlier term paper into your dissertation without telling anyone, typically counts as self-plagiarism.
Building on your earlier work is fine and often encouraged. Ask your instructor or supervisor first, cite your earlier work like any other source, and rewrite rather than copy. Some departments explicitly allow students to develop a term paper into a dissertation chapter if this is declared.
Practical habits that prevent plagiarism
Most plagiarism cases among honest students come from poor note-taking and time pressure, not from intent. These habits close the gaps.
- Mark sources in your notes: put direct quotes in quotation marks with page numbers; write paraphrases with the source attached; label your own ideas clearly (e.g., “ME:”).
- Never copy and paste into your draft without immediately adding quotation marks and a citation.
- Paraphrase from memory: read, close the source, write, then compare.
- Use a reference manager from day one so no source gets lost.
- Cite when in doubt. Common knowledge (facts found in many general sources, like “Paris is the capital of France”) needs no citation; specific data and interpretations do.
- Start early. Panic the night before the deadline is the most common context for plagiarism.
- Ask: if you are unsure about collaboration or reuse rules, ask your instructor in writing.
Plagiarism checkers and similarity reports
Most universities run submissions through a plagiarism checker that compares your text with web pages, publications, and previously submitted student papers. The software produces a similarity report: a percentage and highlighted matches. It does not decide whether you plagiarized. An instructor reviews the matches: correctly quoted and cited passages, common phrases, and your reference list will match too.
There is no universal acceptable percentage. A literature review with many short quotes may show 20 %; a paper with 8 % may still contain one copied paragraph that counts as plagiarism. Focus on proper citation, not on the number. If your university lets you check drafts, use it to find passages you forgot to cite.
Consequences in the US and UK
Penalties depend on the severity, intent, your study level, and whether it is a first offense. Graduate students and repeat cases face harsher outcomes.
| Level | Typical consequences |
|---|---|
| Minor / first offense | Warning, educational workshop, resubmission, reduced grade |
| Moderate | Zero for the assignment, failing the course (US: sometimes an “XF” grade noting academic dishonesty), capped resit mark (UK) |
| Serious | Academic probation or suspension, loss of scholarship, notation on transcript |
| Very serious | Expulsion, withdrawal from the program, revocation of a degree, even years later |
Frequently asked questions
Is self-plagiarism really plagiarism?
At most universities, yes. Resubmitting your own previously graded work without permission is treated as academic misconduct. Ask first and cite your earlier work.
What percentage of similarity is acceptable?
There is no universal threshold. Instructors review the matches themselves; what counts is whether every borrowed passage is properly quoted and cited.
Can you plagiarize by accident?
Yes. Forgetting quotation marks, citing poorly, or paraphrasing too closely can all count as plagiarism, even without intent. Intent may reduce the penalty.
Is using AI considered plagiarism?
It depends on your university and course policy. Submitting AI-generated text as your own without permission or disclosure is usually treated as academic misconduct.
Do I need to cite common knowledge?
No. Facts widely known and found in many general sources need no citation. Specific statistics, interpretations, and arguments always do.
Does Turnitin decide whether I plagiarised?
No. Turnitin and similar programs only show text similarity. Your instructor reviews the matches and decides, taking quotation marks, citations and context into account.
Sources and further reading
- American Psychological Association. (2020). Publication Manual of the American Psychological Association (7th ed.). American Psychological Association.
- Modern Language Association of America. (2021). MLA Handbook (9th ed.). Modern Language Association of America.
- Pears, R., & Shields, G. (2022). Cite Them Right: The Essential Referencing Guide (12th ed.). Bloomsbury Academic.
Your university’s examination regulations and style guide always take precedence.
Related articles
- Quote, paraphrase, summarizeQuote when exact wording matters, paraphrase to restate one idea in your own words, summarize to condense main points. All three need a citation.
- AI in academic writingAI rules vary by university and course. Check the policy, use AI for support rather than ghostwriting, verify every claim, and disclose your use as required.
- Declaration of originalityA declaration of originality is a signed statement that your work is your own, sources are cited, and it was not submitted elsewhere.
- Reference listA reference list contains every source cited in your text; a bibliography may include works you consulted. APA says “References”, MLA “Works Cited”.
- APA 7th editionAPA 7 uses author–date citations: (Nguyen & Patel, 2021) or Nguyen and Patel (2021). Use “et al.” for three or more authors from the first citation.
- Turnitin similarity reportA Turnitin similarity score shows how much of your text matches other sources. It is not a plagiarism verdict: a person judges each match in context.
