Fiscari vs Microsoft 365 Copilot

Can you use Microsoft 365 Copilot for UK tax research?

For drafting and summarising your own documents, yes. As your only source for UK tax research, no: Microsoft says Copilot’s answers can be inaccurate and should be checked. Fiscari answers from UK primary sources, cites the paragraph, and declines when it cannot ground an answer.

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Where Fiscari is stronger

If your firm already pays for Microsoft 365, Copilot is a sensible first thing to try. Microsoft describes it as grounded in the web and, with the Microsoft 365 Copilot licence, in your organisation’s own emails, files and meetings. Those suit your own work. They are not a defined set of UK tax sources, and Microsoft’s documentation does not describe one. Sources, checked 2 November 2026: Microsoft’s Copilot overview, transparency note (application card) and privacy page. This page is about Microsoft Copilot in Microsoft 365, not other products that share the name.

Sources chosen for UK tax

Fiscari retrieves from indexed UK legislation, HMRC manuals, VAT notices and tribunal decisions. Copilot Chat is grounded in the public web, and the paid Microsoft 365 Copilot licence adds your firm’s own data (Microsoft).

A citation to the paragraph

Every Fiscari answer deep-links to the paragraph it rests on, so you can check it against the source. Microsoft says Copilot’s responses can cite the information used to ground them; what it cites depends on what it found on the web or in your files.

It declines rather than guess

Microsoft’s transparency note (application card) says Copilot may include information that is not in its sources, that outputs may be inaccurate or incomplete, and that users should review them. Fiscari is built to refuse when it cannot ground an answer, and publishes that policy.

Easy to test on your own questions

Fiscari has a free account, no credit card, so you can put the same questions through it and through Copilot and compare what each cites.

Head to head

	Fiscari	Microsoft 365 Copilot
Main job	Cited answers to UK tax questions	Drafting, summarising and searching across Microsoft 365 apps
Sources	Indexed UK legislation, HMRC manuals, VAT notices, tribunal decisions	The public web; with the Microsoft 365 Copilot licence, also your organisation’s own data
Citations	Deep-linked to the paragraph	Can cite the information used to ground a response (Microsoft)
When it cannot ground an answer	Declines — published policy	May include information not in its sources; Microsoft tells users to verify
Works inside Word, Excel, Outlook and Teams	No — no Microsoft 365 or Copilot connector	Yes
Works on your firm’s own files	No — public UK sources only	Yes, within the permissions users already have (licence needed)
Price	See the Fiscari pricing	Published by Microsoft: see its UK Copilot plans

Compiled from each vendor's own published material, 2 November 2026. Third-party prices and accuracy figures are those vendors' own published figures. Confirm current terms with the vendor.

Straight about the limits

What Fiscari cannot do

Three things worth knowing before you switch, including the cases where Microsoft 365 Copilot is the better buy.

It does not work inside Microsoft 365

Fiscari has no Microsoft 365 or Copilot connector or plug-in. To draft in Word, summarise an Outlook thread or pull figures from an Excel workbook, Copilot is the better tool, and it works on the files your firm already holds.
We only answer UK tax questions

Fiscari will not draft your client email, summarise a document you paste in or write a proposal. Copilot will. Copilot for the writing and Fiscari for the research is a sensible split.
Public UK sources only

No practitioner commentary, nothing outside the UK, and nothing from your firm’s own precedents or notes. Copilot can draw on those if your firm has the Microsoft 365 Copilot licence.

Worth a look if…

You already pay for Microsoft 365

Keep Copilot for drafting and summarising. Add Fiscari for the question where you would otherwise check the answer on legislation.gov.uk yourself.
The answer has to survive review

Peer review, a client challenge or an HMRC enquiry needs a source you can point at. Microsoft itself tells users to review and verify what Copilot produces.
You want to compare them on your own work

Put the same ten recent client questions through both. See which answers cite the paragraph, and what each does when it is unsure.