Web on or off: when Copilot should search

1When the web helps, when it dilutes the source

Microsoft describes the mechanism. Copilot Chat analyses your prompt, spots the terms for which a search would improve the answer, generates a query and sends it to Bing. Your identifier, your organisation's identifier, the full prompt (unless it is very short) and your attached files never go to Bing. The answer carries clickable citations, and the generated queries stay visible in the conversation for 24 hours.

The word grounding names this link between the answer and a source. Without grounding, the model answers from memory, that is, from what it learned before its cut-off date, with the risk of inventing. The web adds currency and links; it also adds noise if you do not frame it.

Who is in control? The administrator can switch web search off for the whole organisation; Copilot Chat then answers with the model alone. According to the documentation in force in September 2026, Microsoft does not document a per-conversation button for the user without a licence; this point remains uncertain and may vary by interface. The reliable lever is therefore the prompt. To forbid the web: "Do not search the web, work only from the attached files." To require it: "Search the web and give, for every statement, the exact link and the page's publication date."

When to search, when not to. Search for a dated fact (a regulation, a public rate, an announcement), for monitoring or to get an official page. Do not search when the answer must come from your document: a meeting report summary, a quote comparison, a clause extraction. In that case, the web dilutes the source. Point of vigilance: Bing queries leave the European Union data boundary. In other words, those few words may be processed outside Europe, while the rest of the conversation stays inside it. So do not mix confidential content and web search.

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2Remote-work rules, sourced and dated

An HR assistant wants to check something heard in a meeting about remote work.

Weak prompt:

What are the new remote work rules in 2026?

Summarised answer: a confident text that mixes a 2023 press article, a forum and a "reform" with no reference text. No publication date, and two links out of five lead to general pages.

Strong prompt:

Search the web for the rules applying to remote work in the private sector in France on 1 September 2026. Use official sites first (legifrance.gouv.fr, service-public.fr, travail-emploi.gouv.fr), then professional bodies. For every rule: title, reference text, effective date, exact link to the page consulted, publication date of the page. Separate "what the text says" from "interpretation". If you cannot find an official source, say so instead of citing a blog.

Summarised answer: four rules, each with its reference text and a link to a dated official page; an explicit "no official source found" on one point; the interpretation part isolated at the end of the answer.

What changes: the source criteria are set before the search, not after. Every statement is tied to a link and a date, so checkable in one click. The absence of a source is declared instead of hidden.

3Check a VAT rate against official sources

A colleague claims that a reduced VAT rate applies to certain energy renovation works. Here is the starting prompt, to be improved:

"Is it true that VAT is reduced for renovation works?"

Add the web search requirement, the official sites to favour, the date on which the rule must apply, the format (one statement per line with link and date) and the instruction "say so if you cannot find an official source". Run it, then open two links and check that the page really says what Copilot makes it say. The composer below helps you on the Sources, Constraints and Verification fields.

Self-assessment grid: (a) the source criteria and the date are in the prompt; (b) every statement has a link and a date; (c) two opened links confirm the content.

Open the prompt composer