Microsoft 365 for Business: The Complete Guide

Microsoft 365 for business is the subscription suite that brings together Exchange Online email, the Office apps (Word, Excel, Outlook), OneDrive and SharePoint storage, collaboration through Teams, and a layer of security and device management. For an SME, it means working from anywhere, with data kept central and licences that scale per user.

On paper it looks simple: pick a plan, assign the licences and off you go. In practice, across more than 25 years as a B2B system integrator, at TN Solutions we keep seeing companies paying for features they never touch, tenants configured with no security policies, and data that was never actually protected. This guide is here to help you choose the right plan and start on the front foot.

What Microsoft 365 Is and How It Differs from Office

There is still plenty of confusion between "Office" and "Microsoft 365". Office (today also sold as Office LTSC or the perpetual Home & Business licences) is a package you buy once and keep installed on a single PC. Microsoft 365 is a subscription service: you pay per user each month or year and get a great deal more than the desktop apps alone.

The difference that matters to a business is that Microsoft 365 includes the cloud services:

• Exchange Online: business email with shared calendars and contacts, without having to run an in-house Exchange server.
• SharePoint and OneDrive: document storage with granular permissions and version history.
• Teams: chat, video meetings, calls and file sharing in a single workspace.
• Security and identity: Microsoft Entra ID (formerly Azure AD), multi-factor authentication and access policies.

Put simply, with Office you buy a program; with Microsoft 365 you run the collaboration infrastructure for the whole company. It is a shift in approach, not just an upgrade.

The Microsoft 365 Business Plans: Which One to Choose

For SMEs the go-to family is Microsoft 365 Business, designed for up to 300 users. The three main plans differ as follows.

Business Basic

Includes the cloud services (Exchange, Teams, SharePoint, OneDrive) and the Office apps in web and mobile versions only. It does not install Word or Excel on the PC. It suits operational roles that rarely handle complex documents, or companies that already hold desktop licences.

Business Standard

Adds the full desktop Office apps, installable across several devices per user, plus tools such as Bookings and Clipchamp. It is the most popular plan among SMEs because it covers the bulk of everyday needs.

Business Premium

Includes everything in Standard and adds an advanced security and management layer: Microsoft Defender for Business, Intune for device management, conditional access policies and information protection. It is the plan we recommend to companies that want to do things properly without stacking up paid add-ons.

A recurring mistake is choosing a plan on list price alone. A "budget" Business Standard, once you bolt on managed MFA, a third-party antivirus and a separate MDM tool, ends up costing more than a Business Premium, and leaves you with a fragmented setup that is harder to govern. It pays to do the full sum before you sign.

Security: The Part Almost Nobody Configures Well

Switching on Microsoft 365 does not automatically make a company secure. The tenant ships with default settings tuned for maximum compatibility, not maximum protection. The priorities to sort out straight away:

• Mandatory multi-factor authentication (MFA) for every user, not just administrators. It is the single measure that blocks most sign-in attempts made with stolen credentials.
• Conditional access: rules that restrict access based on device, location or session risk (available with Business Premium).
• Anti-phishing and anti-malware policies from Defender, tuned to the company domain.
• Administrative account hygiene: dedicated admin accounts, kept separate from the mailboxes used day to day.
• Logging and auditing switched on, so you can reconstruct what happened after an incident.

Cloud security is bound up with the wider infrastructure: firewalls, endpoints and company networks all need to work in concert. We go into this in more depth in our managed cloud and security services, where the Microsoft 365 tenant is configured as part of a coherent design rather than an island on its own.

Backup: The Responsibility Stays with You

This is perhaps the most misunderstood point of all. Microsoft guarantees the high availability of the service, meaning the infrastructure stays reachable. It does not guarantee that your data can be recovered after a deletion, human error or a ransomware attack beyond the default retention windows (usually a few days or weeks).

This arrangement is called shared responsibility: the platform belongs to Microsoft, the data belongs to you. That is why an independent copy of Exchange, SharePoint, OneDrive and Teams is not an optional extra but part of the baseline design. We have written a dedicated piece on why Office 365 backup genuinely matters for businesses: it is the right read before assuming you are already protected.

How You Move to Microsoft 365: Migration

The most delicate stage is shifting existing data across, email above all. Whether you are coming from an on-premise Exchange server, an IMAP provider or another tenant, the goal never changes: move mailboxes, contacts and calendars without losing email and with minimal downtime.

The main methods are cutover migration (everything at once, suited to a handful of mailboxes), staged migration (in batches) and IMAP migration for generic providers. The choice depends on the number of users, the source system and the outage window you can tolerate. Reconfiguring the domain's DNS records and each user's client is where the most common mistakes tend to cluster.

If you are planning this move, our detailed guide to email migration to Microsoft 365 sets out the methods, timings and risks in full. The rule of thumb: a migration is something you test and prepare for, not something you improvise on a Friday afternoon.

Licences and Management: Avoiding Waste

Once everything is running, the cost of Microsoft 365 depends almost entirely on the number and type of licences. Two habits make a real difference to the budget:

• Review assigned licences regularly. Users who have left the company, over-specified roles, or Premium plans handed to someone who would be fine on Basic are silent costs that pile up month after month.
• Mix your plans. Not every user has the same needs. A warehouse operative and a finance manager can hold different licences, and Microsoft 365 lets you combine them within the same tenant.

Tidy tenant management — licence assignment, user offboarding, security policies — is what separates an environment that is under control from one that grows chaotically. It is exactly the kind of work worth handing to a partner who follows it over time, rather than dealing with it in fits and starts only when something breaks.

Let's Talk: Starting from Your Situation

Microsoft 365 for business works well when plans, security, backup and migration are thought through together, around your real context. TN Solutions has been a B2B system integrator for more than 25 years, holds ISO 9001 and 27001 certifications and is based in Melzo, near Milan: we configure and manage the tenant as part of your infrastructure, not as a disconnected product.

Call us on 02 9517550 or write to us from our contact page: we will look at your requirements together and tell you plainly which plan is right and what to secure first.

Related Service: Managed Microsoft 365 by TN Solutions

If you'd rather hand plans, security and tenant management to a single point of contact, our Microsoft 365 for business page explains how we bundle licensing, security and ongoing support into one service.