When you ask Copilot to generate text, it sometimes includes content you did not want: overly formal language, specific brand names, or lengthy paragraphs. Standard prompts tell Copilot what to do, but they do not always block unwanted behavior. Negative prompting is a technique where you explicitly state what Copilot should avoid. This article explains how to write negative prompts in Copilot for Microsoft 365 and Copilot Pro to get cleaner, more controlled output.
Key Takeaways: How Negative Prompting Works in Copilot
- Explicit exclusion phrases like “do not mention” or “avoid”: Directly instructs Copilot to omit specific topics, words, or tones.
- Place the negative instruction at the end of your prompt: Copilot processes the last instruction with higher priority, improving compliance.
- Use bullet points for multiple constraints: List each “do not” item on its own line to reduce ambiguity and increase accuracy.
What Negative Prompting Does and Why It Works
Negative prompting is a technique borrowed from AI image generation tools, but it works just as well for text models like Copilot. The idea is simple: after telling Copilot what you want, you add a list of things it must not include. This prevents common problems such as hallucinated statistics, overly promotional language, or irrelevant examples.
Copilot uses a large language model that predicts the next word based on the entire prompt you provide. When you include a negative instruction, the model adjusts its probability distribution and avoids tokens associated with the forbidden terms. The effect is strongest when the negative instruction appears near the end of the prompt, because the model assigns higher weight to the most recent context.
No special setting or plugin is required. Negative prompting works in Copilot in Word, Excel, PowerPoint, Teams, and the standalone Copilot chat interface. You simply write the constraints in plain English. The technique is most effective when you combine it with a clear positive instruction about what you do want.
How to Write a Negative Prompt in Copilot
Follow these steps to add negative instructions to any Copilot prompt. The example below uses Copilot in Word to draft an email, but the method applies to all Copilot interfaces.
- Open the Copilot pane
In Word for the web or desktop, click the Copilot icon on the Home tab. The Copilot pane opens on the right side of the document. - Write your positive instruction first
Type what you want Copilot to generate. For example: “Draft a professional email to our vendor about the delayed shipment.” - Add a line break and type “Do not” or “Avoid”
Press Enter to start a new line. Write the negative instruction using clear verbs. For example: “Do not use the word ‘unfortunately’ or any apologetic language.” - List multiple constraints as bullet points
If you have more than one item to exclude, use asterisks or dashes. Copilot treats each line as a separate constraint. For example:
“Do not include specific dates or names.
Do not mention legal action.
Avoid passive voice.” - Press Enter to send the prompt
Copilot processes the entire prompt and generates a response that respects both the positive and negative instructions. Review the output and refine the negative list if needed.
If Copilot ignores a negative instruction, rephrase it as a positive command. For example, instead of “Do not use bullet points,” write “Use full paragraphs only.” The model sometimes responds better to positive phrasing for structural instructions.
Common Negative Prompting Mistakes and How to Fix Them
Copilot still includes forbidden terms
If Copilot generates text that contains a word or phrase you told it to avoid, the negative instruction may be too vague. Replace general words like “avoid jargon” with specific terms. For example: “Do not use the terms ‘synergy,’ ‘leverage,’ or ‘paradigm shift.'” Specificity forces the model to exclude exact tokens rather than a broad concept.
Negative instruction reduces output quality
Too many negative constraints can make Copilot produce short or incomplete sentences. Limit your negative list to three items maximum. If you need more constraints, prioritize the most critical ones. You can also split the task into two prompts: one for structure and one for tone.
Copilot repeats the negative instruction in the output
Occasionally, Copilot echoes your “do not” phrase back in the generated text. To prevent this, place the negative instruction after a separator like “—” or after the phrase “Constraints:”. For example: “Draft a product description. Constraints: Do not mention price or competitors.” The separator helps the model distinguish between the instruction and the content it should generate.
Negative prompting does not work in Copilot in Excel
Copilot in Excel focuses on formulas, charts, and data analysis, where negative prompting has limited effect. Use negative instructions only for text-based tasks like generating email drafts, document summaries, or presentation talking points. For Excel, use direct positive commands such as “Show only rows where sales exceed 1000.”
Positive Prompt vs Negative Prompt: Usage Scenarios
| Item | Positive Prompt | Negative Prompt |
|---|---|---|
| Definition | Tells Copilot what to include or do | Tells Copilot what to exclude or avoid |
| Example | “Summarize the meeting notes in three bullet points” | “Do not include attendee names or action items” |
| Best for | Defining structure, length, and format | Removing unwanted tone, terms, or topics |
| Limitation | May still include undesired content | Can reduce fluency if overused |
| Recommended order | Place first in the prompt | Place last in the prompt |
Use both types together for the best results. A positive prompt sets the direction, and a negative prompt removes the noise. For example: “Write a one-paragraph project update. Do not mention delays or budget issues.” This combination gives Copilot a clear target and a clear boundary.
You can now control Copilot output more precisely by adding negative instructions to your prompts. Start with one or two constraints and test the results. For advanced control, combine negative prompting with Copilot’s tone setting in the Copilot pane under Settings > Tone. This lets you set a base tone like “Professional” while also excluding specific words.