If your company is still using standalone Office licences, an outdated on-premises mail server or mailboxes from different providers, Microsoft 365 is probably the most cost-effective move you can make this year. It is not just Word and Excel: it is a productivity, communication, security and — since late 2025 — integrated artificial intelligence platform. The question is not whether to adopt it but which of its plans fits your SMB and how to implement it without causing internal disruption. This article answers both questions with current data and no beating around the bush.
What is Microsoft 365 Business and how does it differ from Office?
Office was a software package installed once on a computer and left there until the licence expired. Microsoft 365 is a monthly per-user subscription service that includes the Office applications plus a cloud services layer: corporate email with Exchange Online, storage with OneDrive (1 TB per user), collaboration with Teams and SharePoint, and a centralised administration panel from which to manage all users, devices and permissions.
The key difference for an SMB is that with M365 there is no mail server to maintain, application updates arrive automatically, and access is available from any device and location. For a company with remote employees or multiple offices, this radically simplifies IT operations.
The three Business plans explained without jargon
Microsoft offers three plans aimed at organisations of up to 300 users. Each one adds functionality on top of the previous. Here is the comparison that matters most to an SMB director:
| Feature | Business Basic | Business Standard | Business Premium |
|---|---|---|---|
| Desktop Office apps (Word, Excel, PowerPoint…) | No (web and mobile versions only) | Yes | Yes |
| Corporate email (Exchange Online) | Yes | Yes | Yes |
| Microsoft Teams (meetings, chat, calls) | Yes | Yes | Yes |
| OneDrive (storage per user) | 1 TB | 1 TB | 1 TB |
| SharePoint (intranet and document management) | Yes | Yes | Yes |
| Microsoft Defender for Business (antivirus and EDR) | No | No | Yes |
| Device management (Intune Plan 1) | No | No | Yes |
| Conditional access and advanced MFA (Entra ID P1) | No | No | Yes |
| Anti-phishing and anti-malware protection (Defender for Office 365 P1) | No | No | Yes |
| Maximum number of users | 300 | 300 | 300 |
Which one to choose? Business Basic is sufficient if your employees work mostly from a browser and do not need Office installed on the desktop. Business Standard is the most common plan for SMBs where Office files are regularly worked on locally (quotes in Excel, reports in Word, presentations in PowerPoint). Business Premium is the recommended option if you handle sensitive data, have corporate computers you want to manage centrally, or if your sector requires stricter security measures (legal, healthcare, finance, industry with suppliers that impose cybersecurity requirements).
Microsoft 365 Copilot Business: the AI that arrived in December 2025
Since 1 December 2025, Microsoft has been selling Microsoft 365 Copilot Business, an artificial intelligence layer designed specifically for organisations of between 1 and 300 users. It is added as an add-on to any of the Business plans and enables AI integrated directly into Word, Excel, Outlook, Teams and PowerPoint.
In practice, Copilot Business allows things such as:
- Summarising long email threads or Teams meetings with one click, without having to re-read the entire conversation.
- Generating document or email drafts from natural language instructions ("write a commercial proposal for this client based on these points").
- Creating complete presentations from a Word file or a text summary.
- Analysing data in Excel with intelligent suggestions and automatic charts.
- Connecting to external sources such as Slack, Google Drive or Confluence to consolidate dispersed information.
For an SMB without a dedicated IT department, Copilot Business reduces the friction of adopting AI: there is no new tool to learn, it works inside the applications the team already uses every day. If you want to know more about how to integrate Copilot into your company's workflows, at Summum Sistemas we implement it as part of the Microsoft 365 implementation service.
What happens to existing emails and data during migration
One of the questions that most concerns SMB directors before migrating is what happens to the email history, contacts and calendars. The answer is that everything can be migrated. Microsoft provides migration tools for the most common scenarios:
- From Google Workspace (Gmail, Google Calendar, Google Contacts): direct migration via the Microsoft 365 Admin Center, without third-party tools.
- From an on-premises Exchange server: hybrid or staged migration, which allows both environments to remain active during the process.
- From another IMAP provider (OVH, Arsys, Rackspace, etc.): native IMAP migration that copies emails folder by folder.
- From legacy Office 365 or perpetual licences: the process is simpler because there is already a Microsoft infrastructure in place.
The critical point is not technical but organisational: deciding the cut-over date, communicating it to the team with enough lead time and having a contingency plan for the first 48 hours. In well-planned projects, email downtime during migration is virtually zero.
Included security: what Business Premium provides that most SMBs lack
In Spain, security breaches in SMBs increased significantly between 2023 and 2025, according to annual INCIBE reports. The typical problem is not the absence of antivirus software, but the lack of control over devices, weak passwords without a second authentication factor, and email accounts without advanced phishing protection.
Business Premium integrates three layers of protection as standard that solve these problems without the need to contract additional solutions:
- Microsoft Defender for Business: antivirus and EDR (endpoint detection and response) that monitors devices in real time and alerts against anomalous behaviour.
- Microsoft Intune Plan 1: allows the administrator to apply policies across all corporate devices (Windows, Mac, iOS, Android): disk encryption, remote wipe if a computer is lost, restriction of access to unauthorised applications.
- Defender for Office 365 Plan 1: analyses links and attachments in emails before they reach the inbox, blocking phishing campaigns and malware.
For many SMBs, this set of security tools included in Business Premium replaces standalone solutions whose combined licence costs would exceed the price of the full plan.
How the implementation process works step by step
An orderly Microsoft 365 implementation in an SMB follows these phases. Timelines vary depending on the number of users and the complexity of the source environment, but for a company of between 10 and 50 users the complete process usually takes between 3 and 6 weeks.
Phase 1: Audit of the current environment
Before touching anything, you need to inventory which email accounts exist, which Office applications are installed on each machine, where shared files are stored (local server, NAS, Dropbox…) and what integrations exist with management software (ERP, CRM, accounting tools). This audit prevents surprises during migration.
Phase 2: Tenant design and user profiles
The Microsoft 365 environment (the "tenant") is created, email domains are configured, security groups are designed and licence types are assigned by user profile. Not all employees need the same plan: an administrative profile may need Standard while the management or sales team may benefit more from Premium.
Phase 3: Email and data migration
Mailbox, contacts and calendar migration is carried out. In parallel, SharePoint is configured as a replacement for the local file server: document libraries, department permissions and OneDrive synchronisation on users' computers are set up.
Phase 4: Training and adoption
The most common failure in M365 implementations is not technical: it is that users carry on working as before because no one has explained the new tools to them. A training session per profile (general users, Teams users, administrators) makes the difference between a project that gets used and one that is abandoned after a week.
If you need support throughout the process, from the initial audit to team training, our Microsoft 365 implementation service covers each of these phases with a dedicated consultant.
Microsoft 365 and electronic invoicing: the integration on its way
With the approval and upcoming entry into force of the B2B electronic invoicing obligation in Spain (Ley Crea y Crece and the Verifactu regulation, with mandatory compliance deadlines from 2027–2028), many SMBs are evaluating how to integrate their productivity suite with their invoicing tools. Microsoft 365 is not itself an invoicing system, but it is the platform from which the associated document management can be automated: receiving invoices in Outlook, storing them in SharePoint, approval workflows with Power Automate.
If your company uses a compatible ERP (Dynamics 365, Sage, Odoo or others), the integration with M365 makes it easier for tax documents to flow between systems without manual intervention. This type of integration is part of the work we regularly carry out at Summum Sistemas when implementing M365 alongside a broader digitalisation project.
Frequently asked questions
Can I mix different plans within the same company?
Yes. Microsoft 365 allows you to assign different plans to each user within the same tenant. It is common for a company to assign Business Basic to employees who only need email and Teams, Business Standard to those who work with desktop Office, and Business Premium to profiles with access to sensitive information or corporate devices to manage. The invoice reflects exactly the licences of each type that you have active.
What happens if I exceed 300 users?
Business plans have a design limit of 300 users. If your company grows beyond that threshold, the natural migration is towards Microsoft 365 Enterprise plans (E1, E3 or E5), which have no user limit and offer additional functionality for regulatory compliance, advanced analytics and more granular identity management. The transition between Business and Enterprise plans is technically straightforward and involves no data loss.
Does Microsoft 365 comply with the GDPR?
Microsoft acts as a data processor for the data you store in M365 and complies with the General Data Protection Regulation (GDPR). The data centres in the European region (including the Western Europe zone) ensure that data does not leave EU territory by default. Microsoft publishes its compliance certifications (ISO 27001, SOC 2, ENS Alto for Spanish Public Administration clients) on the Microsoft Service Trust Portal. However, responsibility for correctly configuring permissions, retention policies and access rests with the company as the data controller: M365 gives you the tools, but they must be used correctly.
How long does an implementation take and what disruption does it cause?
For a company of between 10 and 50 users, a planned implementation takes between 3 and 6 weeks from the start of the audit to final team training. The email migration, which is the most critical moment, is usually carried out over a weekend to minimise impact. With good planning, email service downtime during migration is reduced to less than one hour. The remaining services (Teams, SharePoint, OneDrive) are activated progressively without affecting daily operations.