Which Microsoft 365 plan do UK accountants need?

Microsoft 365 Business Premium (£17.75/user/month). It includes Intune device management, Defender for Business and Entra ID P1 — the tools you need to evidence ICAEW/ACCA information security expectations and PI insurance requirements.

Is Microsoft 365 backed up?

Not against user error or ransomware. Microsoft protects against their own infrastructure failures, but if a user deletes a client folder and it's not noticed within ~30 days, it's gone. Accountancy practices should add third-party Microsoft 365 backup (around £3-4/user/month).

Does Microsoft 365 integrate with Xero, Sage and QuickBooks?

Yes, all three have Outlook and Teams integrations. Xero has direct bank-feed integration inside Outlook. Sage syncs with Outlook calendars. QuickBooks has an Outlook add-in for linking emails to transactions.

Can I use Microsoft 365 with my on-premise IRIS or CCH install?

Yes. On-premise accountancy software and Microsoft 365 coexist fine. You can use Azure AD Connect to sync user accounts, and Intune to enforce security policies on the Windows machines running the software.

Microsoft 365 for Accountants UK (2026): The Practical Guide

Last updated: April 2026

UK accountancy practices are Microsoft 365's sweet spot — and the plan choice is usually the same: Business Premium. You handle client financial data, you're overseen by ICAEW / ACCA / AAT, you have AML obligations, and your staff work on personal devices more than they admit.

Here's how to set up Microsoft 365 correctly for a UK accountancy firm, and what it genuinely costs.

Why Business Premium is the right tier for accountants

Business Standard gets you the productivity apps (Word, Excel, Outlook, Teams). That's fine for a florist. For an accountancy firm it leaves gaps:

Client data is on staff laptops and phones. Someone loses a phone on the train. What happens to the emails containing client bank details, NI numbers, UTRs?
Staff use personal devices. Every junior checks work email on their own phone. Every senior has a laptop that travels. Without Intune, you can't enforce basic security.
ICAEW and FRC audit requirements expect you to demonstrate control of client data access. Without Entra ID P1, you can't evidence conditional access policies.
Insurance. Most PI insurers for accountants now require specific endpoint controls. Business Premium ships with them.

Business Premium at £17.75/user/month gives you Defender for Business, Intune and Entra ID P1 included. For a 10-person firm that's £213/month, or about £2,550/year. Cheap for what it does.

What you need beyond Microsoft 365

Endpoint protection

Business Premium includes Defender for Business — enterprise-grade antivirus and EDR. You don't need a separate antivirus unless you prefer a non-Microsoft option (see Avast vs Defender).

Email security

Exchange Online Protection (included in all Microsoft 365 Business tiers) handles spam and basic phishing. For accountancy practices — regularly targeted by invoice fraud — we recommend adding Microsoft Defender for Office 365 Plan 1 (£1.72/user/month) on top. It gives you Safe Attachments and Safe Links, specifically designed to catch the "urgent invoice" scams accountants see weekly.

Secure file sharing with clients

Don't send client tax returns, bank statements or payroll over email. Use OneDrive or SharePoint links with expiry dates and password protection. Business Standard and Premium both include this; make sure staff actually use it. A 15-minute training session pays for itself.

Backup

Microsoft 365 is not backed up by Microsoft against staff mistakes or ransomware. If a user deletes a client folder and it's not noticed for 95 days, it's gone. Add a third-party Microsoft 365 backup product (Acronis, Datto, SpinBackup) at around £3-4/user/month. For any firm with client financial data, this is non-optional.

VoIP

Most accountancy firms still run on a patchwork of mobiles, a desk phone, and a landline that rings in reception. Proper cloud VoIP (call recording for compliance, call forwarding, softphone apps for home working) is £10-12/user/month. Bundle it with Microsoft 365 through CTN and save 10% on the M365 side.

Integration with accounting software

Microsoft 365 plays nicely with the UK accountancy software stack:

Xero: direct integration for bank feeds from Outlook; Xero HQ works in a browser regardless
Sage: Sage 50 and Sage Business Cloud both run alongside Microsoft 365 happily; Sage Cloud syncs with Outlook calendars
QuickBooks Online: add-in for Outlook to sync emails with transactions
IRIS: mostly desktop; runs on Windows machines managed by Intune
CCH (Wolters Kluwer): on-premise install; policies via Intune; documents stored in SharePoint

If you're running on-premise accountancy software, you can still use Microsoft 365 for email, productivity and device management. The two coexist fine.

Typical setup for an accountancy firm

Sole practitioner (1 user)

Microsoft 365 Business Premium (£17.75/month)
Defender for Office 365 Plan 1 add-on (£1.72/month)
Third-party Microsoft 365 backup (£3.50/month)
Total Microsoft stack: ~£23/month
Plus VoIP: a single user VoIP seat (~£10/month) with bundle discount

Small firm (5 partners + 3 staff)

8 × Microsoft 365 Business Premium (£142/month)
8 × Defender for Office 365 (£13.76/month)
8 × third-party backup (£28/month)
Microsoft stack: ~~£184/month (~~£2,200/year)
Plus VoIP for 8 extensions with call recording (~£120/month)
10% bundle saves ~£220/year on Microsoft

Mid-sized practice (25 users)

25 × Microsoft 365 Business Premium (£444/month)
25 × Defender for Office 365 (£43/month)
25 × backup (£87.50/month)
Optionally 8 × Copilot for partners and seniors (£194/month)
Microsoft stack: ~£575/month without Copilot, ~£770/month with (£6,900-£9,200/year)
Plus VoIP for 25 extensions (~£350/month)

AML and GDPR — the bit that sells Premium to partners

ICAEW, ACCA and HMRC all expect accountancy practices to have documented information security policies covering:

Identity and access management
Device management
Data protection and retention
Incident response

Microsoft 365 Business Premium gives you the tools to evidence each of these:

Conditional access policies (Entra ID P1) — evidence of who can access what, from where
Device compliance policies (Intune) — evidence that client data isn't on unmanaged devices
Data loss prevention — evidence that NI numbers, bank details, etc. aren't leaving the tenant
Audit logs — 90 days minimum retention of every user action

For AML-regulated practices, this matters. Being able to produce policies from a single admin portal beats piecing it together from three products.

The "bring your own device" problem

Junior accountants check email on their personal phones. Partners use their personal laptops from home. This is normal. It's also a GDPR problem.

Without Intune: you have no control. If a phone is lost, you're relying on Apple or Google's find-my-phone features (and the owner actually using them). If someone leaves for a competitor, their personal device still has your client emails.

With Intune (included in Business Premium):

You can require a PIN and auto-lock on any device accessing work email
You can remote-wipe only the work data (leaving personal data alone) from a lost or decommissioned device
You can block access from unmanaged devices entirely

This is the killer feature for accountants. £17.75/month/user to have this is a bargain.

Why bundle your Microsoft 365 and phones with CTN

Most practices we work with used to have:

Microsoft 365 through an IT reseller
A VoIP or landline setup through a phone company
Mobile phones through a network or reseller
Antivirus from an IT guy
Four different invoices

Bundling Microsoft 365, VoIP and business mobile through one UK supplier gets you:

One monthly invoice (your bookkeeper says thank you)
One UK phone number for support issues
One account manager who understands your practice
10% discount on Microsoft 365 when taken with CTN VoIP
Aligned renewal dates so you negotiate everything once every 24 months instead of three times a year

FAQs

Can I get Microsoft 365 through my existing IT company?

Yes, most IT companies resell Microsoft 365. Whether you should depends on their pricing (some mark up above Microsoft RRP), their support quality, and whether you'd bundle with phones. If your IT company is good, stay. If it's a set-and-forget pay-through-the-nose relationship, it may be worth moving.

Does Microsoft 365 work with my Windows Server?

Yes. Microsoft 365 Business plans include tools (Azure AD Connect) to sync your on-premise Active Directory with Microsoft 365. Common setup for firms still running an office file server alongside SharePoint.

Do I need Microsoft 365 E3 instead of Business Premium?

Almost certainly not. E3 is priced for enterprises and most of its extras (advanced compliance, legal hold, enterprise mobility) overshoot what a practice under 300 staff needs. Stick with Business Premium.

What about Copilot for accountants?

Useful for senior staff drafting client letters, summarising long email threads, and analysing management accounts in Excel. Less useful for juniors doing compliance work where AI output needs full manual verification anyway. Most firms we see license Copilot to partners and seniors only — typically 20-30% of staff.

Can you migrate us at our year-end?

Yes. Scheduling Microsoft 365 migration for July-August avoids year-end chaos for firms on April reporting. We coordinate around your busy periods.