Microsoft 365: A Lawyer’s Guide to Subscription Plans, Copilot and Document Management

By Frank Manning, Carton & Co. Updated 26 October 2026.

In short. For most UK law firms with up to 300 users, Microsoft 365 Business Premium (£16.90 per user per month) is the right base plan, because it adds the security, device management and data protection that client information needs.

Copilot Chat is included with Business Basic, Standard and Premium at no extra cost. Microsoft 365 Copilot Business (for up to 300 users) adds Copilot in Word, Excel, PowerPoint, Outlook and Teams, drawing on the firm's own data, for £16.10 per user per month (£13.80 for the first year on Microsoft's promotion for existing business customers, annual commitment, to 31 December 2026). Review SharePoint and OneDrive permissions before switching Copilot on.

Use OneDrive for personal drafts and SharePoint for matter files and anything the team works on together.

Most lawyers use Microsoft 365, but with all the renaming and frequent upgrades it can be tricky to work out which subscription is best for your practice and how to make the most of features you might not have tried yet.

Picking the right subscription plan is key to meeting your productivity, security and compliance needs. Copilot now brings AI into the same applications, which makes permissions and data protection more important than before. Knowing the differences between OneDrive and SharePoint also helps you manage documents more effectively.

Microsoft 365 subscription plans

Technology is crucial now for lawyers' productivity, data security and collaboration. Microsoft 365 offers various subscription plans suited to law firms, each with its own features and benefits. Prices here are Microsoft UK list prices per user per month for an annual commitment, excluding VAT. Microsoft's list prices changed on 1 July 2026 (existing customers move to the new prices at renewal). Business Premium now costs £6.10 per user per month more than Business Standard.

🧿 Business Basic

Microsoft 365 Business Basic is the most affordable option, providing web and mobile versions of Word, Excel, PowerPoint and Outlook. It includes business email on the firm's own domain, 1 TB of OneDrive storage per user, SharePoint and Microsoft Teams. It does not include desktop versions of the Office apps, which makes it less suitable for intensive document work. Its security is limited to spam and malware filtering and link checking. Pricing: £5.40 per user per month.

🧿 Business Standard

Microsoft 365 Business Standard adds desktop versions of the Office applications (such as Word, Excel and Outlook) to everything in Business Basic. Business Standard suits firms that need comprehensive productivity tools, but it lacks the advanced security features of Business Premium. Pricing: £10.80 per user per month.

🧿 Business Premium

Microsoft 365 Business Premium is the plan we recommend for most law firms. It includes all the apps and services in Business Standard along with advanced security and device management: Microsoft Defender for Business, Defender for Office 365 and Microsoft Intune protect devices and email, which is crucial for law firms handling confidential client information. It also includes Microsoft Purview sensitivity labels, data loss prevention for email and files and message encryption. Pricing: £16.90 per user per month.

Firms that want more protection can add the Microsoft Purview Suite and the Microsoft Defender Suite for Business Premium, at £7.70 per user per month each or £11.50 for both. The Purview Suite adds automatic classification and labelling, records management, advanced message encryption and insider risk detection.

🧿 Microsoft 365 E3

Microsoft's business plans are limited to 300 users across the firm, so firms above that need enterprise plans such as Microsoft 365 E3. E3 includes Defender for Office 365 from July 2026. Copilot Business is only for the business plans, so firms on E3 need Microsoft 365 Copilot, the enterprise version, which is priced separately. Pricing: £33.50 per user per month.

🧿 Personal and Family plans

The Microsoft 365 Personal and Family plans are not suitable for law firms. These plans are designed for individual and family use and lack business features such as email on the firm's own domain.

🧿 Plans without Teams

Microsoft also sells versions of the business plans without Teams, for example Business Basic (no Teams) at £4.20 per user per month. These only make sense where the firm uses another platform for calls, meetings and chat.

🧿 Prices at a glance

Microsoft UK list prices, annual commitment, excluding VAT, 26 October 2026.

Choosing the right Microsoft 365 subscription should be based on the specific needs of your law firm. For most firms, Business Premium offers a comprehensive set of tools and enhanced security at a reasonable cost. Sole practitioners may find Business Standard sufficient. Firms with more than 300 users need E3 or another enterprise plan. Personal and Family plans should be avoided for professional use. Business plans can be mixed within the 300-user limit, so each person can have the licence their work needs.

🧿 Adding Copilot for built-in AI

Copilot Chat. Business Basic, Standard and Premium include Microsoft 365 Copilot Chat at no extra cost. It is an AI assistant grounded in web content. It works with files a person uploads or has open and, in Outlook, with their own email and calendar. It does not search the firm's SharePoint and OneDrive content as a whole. For many firms it is the right place to start.

Copilot Business. Microsoft 365 Copilot Business is the full Copilot for the business plans. It works inside Word, Excel, PowerPoint, Outlook and Teams and draws on the firm's own data automatically, so a lawyer does not need to upload documents to it. It is available for up to 300 users.

Disappointingly, there is still some scepticism about how capable Copilot is, but it is improving quickly and is likely to become a key tool for lawyers. Exploring and planning how best to implement it should be a priority now.

Pricing. Copilot Business costs £16.10 per user per month, with a promotional price of £13.80 between 1 July and 31 December 2026 for existing customers with an eligible business plan (annual commitment, first year only). Microsoft also sells Business Standard and Business Premium with Copilot included, at £18.10 and £24.60. Both bundles cost less than the plan plus the Copilot Business add-on, so firms adding Copilot for most of their people should compare the two. Copilot Business is licensed per user, so a firm can start with a pilot group working on agreed tasks.

Before you switch Copilot on

Permissions. Copilot respects existing permissions: it can see whatever the person using it can open. That includes documents that were shared too widely in the past, which Copilot will find and summarise. SharePoint's default sharing settings are the most permissive option, so a review of who can see what should come first, including sites open to everyone in the firm, "Everyone except external users" permissions and old sharing links.

Labels. Business Premium includes Microsoft Purview sensitivity labels and data loss prevention. Sensitivity labels mark and protect confidential matter documents.

What Copilot can see. Copilot works with the firm's data in Microsoft 365. Documents held in a case or practice management system are outside its reach unless the system stores them in SharePoint or is linked through a Microsoft 365 Copilot connector, which needs a connector for that system and Copilot Business licences. Check where your matter documents actually live before deciding what Copilot can do for the firm.

💙 OneDrive vs 💚 SharePoint: key differences and use cases

For legal professionals, understanding the differences between OneDrive and SharePoint is key to effective document management and collaboration.

Ownership and accessibility

💙 OneDrive is designed for personal storage and file sharing, functioning as each user's personal online filing cabinet. Documents in OneDrive are private until the person shares them. 💚 SharePoint makes files accessible to a group, a department or the entire firm. The team can own them together.

💙 OneDrive is ideal for individual workspaces, where drafts, notes and personal documents are saved before they are finalised and shared. It keeps files backed up and available on any device, supporting a mobile and flexible work style. When a document is ready to be reviewed or worked on together, it can be shared with specific individuals who can then edit or comment on the file.

💚 SharePoint, on the other hand, is built to manage and organise files in a collaborative environment. It provides structured storage by organising documents according to specific matters, clients or projects, ensuring everyone on the team has access to the most up-to-date information. SharePoint libraries also support built-in approvals and Power Automate flows.

💚 SharePoint offers document management features (such as extra columns to categorise and track files, custom views, check-out and permissions) which help organise large volumes of documents. This is useful for law firms that deal with extensive documentation.

While OneDrive serves as an excellent tool for personal document management and initial drafting, SharePoint stands out as the preferred solution for collaboration, document organisation and team productivity within legal practices.

Scope for sharing documents

💙 OneDrive is most suitable for storing personal work files, drafting documents before sharing them with a team or client and securely sharing a single document. 💚 SharePoint excels in matter-centric storage by organising documents according to matters, clients or legal projects, making it easier for teams to work together on shared documents such as court documents, contracts and statements of case.

Collaboration style

💙 OneDrive is ideal for one-to-one or small-group collaboration, while 💚 SharePoint supports collaboration across a team, a department or the whole firm, including sharing with people outside the firm where that is allowed.

Document versioning and co-authoring

Both OneDrive and SharePoint keep previous versions of documents, so users can track changes and restore earlier versions. Both support co-authoring, where several people edit a document at the same time.

Integration with Teams

Files shared in a Teams channel are stored in the team's SharePoint folder. Files sent in a one-to-one or group chat are stored in the sender's OneDrive and shared only with the people in that conversation.

When to use OneDrive vs SharePoint for legal work

💚 Use SharePoint for structured team and firm-level collaboration, finalised document libraries, matter management and knowledge sharing, such as:

• Matter management. Create separate document libraries or SharePoint sites for each matter. Centralise statements of case, instructions to counsel, client correspondence and court documents.
• Client access. Provide controlled access for clients to view documents and matter progress securely.
• Knowledge management. Store templates and precedents (contracts, legal research) centrally for easy retrieval. Share internal training, CPD resources, policies and best practice.
• Firm-wide policies and procedures. HR policies, firm manuals, guidelines, onboarding material for new staff and compliance documentation.
• Collaboration and project management. Version-controlled document editing, feedback and document check-out to prevent accidental overwrites. Project planning (for example internal audits, mergers and litigation strategy).

💙 Use OneDrive for individual productivity, personal drafts and temporary document storage and sharing, such as:

• Personal drafts and research. Draft legal memos, initial case research, private annotations and personal notes before documents are finalised and moved to a SharePoint library.
• Short-term sharing. Temporarily share a document with colleagues for quick review or edits before it is finalised.
• Backup and mobility. Files backed up and available on any device, helpful for remote work, meetings and travel.
• Confidential individual files. Personal career development documents, appraisals, private notes, performance feedback and individual professional documentation.

Conclusion

Selecting the right Microsoft 365 plan and mastering document management is essential for any law firm. Whether you choose Business Standard for its tools, Business Premium for its enhanced security or E3 for a firm above 300 users, an informed choice will support your firm's productivity and security. With Copilot, the order matters: permissions and labels first, then a pilot group, then wider rollout.

Use OneDrive for personal storage and SharePoint for collaborative work to keep your documents organised and accessible. By doing so, you can ensure that your firm's digital infrastructure is both efficient and secure.

The Microsoft 365 suite also has a number of specialised applications that your firm may be able to put to good use, such as Microsoft Visio (a separate licence) for process mapping and improvement, although you might also be tempted by other options like Lucid, which we use too.

As with all software applications, the benefits realised are proportional to how much you engage with these products. Many firms could gain much more value by doing more with their investment in Microsoft 365.

For more guidance on selecting the right options for your law firm, get in touch. Carton & Co is independent and does not sell Microsoft licences. We can give you a comprehensive evaluation of the options that will be the best fit for your particular practice, systems and needs.

Contact: Frank Manning
Email: fmanning@cartonconsultants.com
Mobile: 07778 572420

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Note: Prices are Microsoft UK list prices, per user per month, annual commitment, excluding VAT, as of 26 October 2026.

Author bio

Frank Manning is the technology specialist at Carton & Co, advising law firms on technology strategy, practice and case management system selection, Microsoft 365, IT reviews and project delivery. He has over 25 years’ hands-on experience across professional services and other sectors, with projects delivered in the UK, Europe, the Americas and Asia.