Forum Discussion
Copilot confused by the term "last week"
Your findings are fully correct. The underlying LLM does know the exact date only based on your "last week" prompt information. I know – we would expect that the LLM does know the current date as it works when you ask for the current date. Keep in mind with such date-specific questions that it is easier for Copilot to understand your question if you add either the current week or at least the current day we have now. The reason is simple: There is math required for the LLM to get this information, and just "last week" is not enough for the LLM to execute this math. We as humans can do this, as we work in days/weeks/months/years, but LLMs do not.
PeterForster
Not exactly, as you can see from the example I posted, if you ask the question "What are the dates of last week ?", the answer is correct and I did not encounter any occurrence where Copilot would not answer this question properly. However, when the term "last week" is used in a broader query, Copilot fails to retrieve the correct date range.
Microsoft is actually using the https://www.microsoft.com/en-us/microsoft-copilot/for-individuals/do-more-with-ai/ai-for-professional-life/summarize-missed-emails-with-copilot-pro?form=MA13KP so I disagree with your idea that we should not expect Copilot to answer this properly. If LLM can not do this, Microsoft should not advertise it.
I completely understand your frustration, especially given that Microsoft has officially announced this feature. I’ve re-checked the current Microsoft 365 Copilot roadmap and noticed that at least some of the mentioned date ranges should now be functional as of June 10, 2025.
While I can’t provide a direct link to the specific section, you can find this information in the Microsoft 365 Copilot Release Notes on Microsoft Learn—just search for the term “week.”:
Release Notes for Microsoft 365 Copilot | Microsoft LearnImportant: This functionality is currently only available in Copilot Chat at https://m365.cloud.microsoft/chat specifically within the “Work” section. I ran a few tests myself, and it seems to be working quite well.
I receive too many emails to verify every entry, but at the very least, it does show me some of my messages. Keep in mind that while prompts like “last week” are now supported, there are still limitations on the number of references that can be returned in a single chat window—so not all messages from last week may be included in the response.