Microsoft 365 / How Teams, Microsoft 365 groups and SharePoint sites connect

When you create a team in Microsoft Teams, its membership is managed through a Microsoft 365 group, and standard-channel files are stored in the connected SharePoint site. Understanding the actual storage location and permission structure helps you manage the files you see in Teams. These are distinct services with connected resources.

Roles of the three components

According to Microsoft's Teams and SharePoint integration document, standard channels use a folder for each channel within the team's default SharePoint site. Private channels and shared channels use separate channel sites, so the same access permissions as standard channels should not be assumed.

What happens when a team is created?

1. During the team creation process, a new Microsoft 365 group is created or an existing group is connected to the team.
2. The team owner-member relationship is connected to the group, and the default SharePoint team site is used as the file storage.
3. Files uploaded to a standard channel are managed within the document library of the connected site. Files in private or shared channels are stored in a separate channel site.

Teams and SharePoint can show the same stored file, so editing or deleting it in one interface can affect what you see in the other. Check the actual site and library before acting. Files uploaded to a one-to-one or group chat are stored in the uploader’s OneDrive for Business and shared with that conversation; they are not automatically channel files or files in a personal consumer OneDrive. Microsoft’s Teams file storage guide distinguishes channel and chat storage.

How does file space vary depending on the type of channel?

For example, if a product project team has standard channels for “Planning” and “Design,” the two channels use different folders on the same underlying site. Simply creating a design channel does not mean that only designers can access that file. If it is a contract negotiation handled by only certain personnel, you need to determine whether a separate access boundary, such as a private channel, is necessary.

Shared channels are different from adding external people as guests to the whole team. Since external participation also involves cross-organization collaboration settings, do not interpret the name “shared” to mean you can send a link to anyone. The privacy setting of a team and the privacy setting of a channel are also different levels.

The table describes the default membership boundary, not every possible file-sharing grant. Under permitted SharePoint sharing settings, individual files or folders can have separate links or permissions; accessing a file does not make someone a member of the channel conversation. Microsoft documents these file-access considerations for private channels. Shared-channel files have additional limits: sharing with an external person who is not a channel member is unsupported. External channel participation uses Microsoft Entra B2B (business-to-business) direct connect and requires the relevant cross-tenant configuration; it differs from adding a guest account to the team. See Microsoft’s shared-channel access guidance.

Where should permissions be changed?

When adding or removing team members, it is generally easier to understand if managed around Teams’ team members or the connected Microsoft 365 group. If you grant separate permissions only on the SharePoint site, that user may have access to the site but may not be a member of the Teams team. Microsoft recommends managing the members of a Teams-connected site centered on Teams under Managing permissions of a Teams-connected site.

In particular, members of private or shared channels on the site must be managed in the respective channel in Teams. They are not handled like regular sites where members can be changed independently in SharePoint. On the other hand, if you add someone as a site visitor who only has read access to documents in the default team site, that person will not automatically become a member who can see the team conversation. When using exception permissions, record why it is necessary so it won’t be missed during future access reviews.

How to verify the actual file storage location

1. In Teams, select the team and channel to investigate. Since there can be multiple channels with the same name in different teams, also record the team name.
2. Open the channel's file area. Depending on the client version, it may appear as Files or Shared, etc. Distinguish it from the list of attachments in chat.
3. Select Open in SharePoint and check the site address, library, and folders opened in the browser. Viewing the file's URL serves as a basis for determining the actual location.
4. Verify it in other standard channels of the same team as well. The base site address is expected to be the same, with folders differing by channel. Check whether private or shared channels are linked to separate sites.
5. Without changing the settings, view the file and then record the team, channel type, site address, and administrator responsible in the work log. Do not put the actual private file address in documents that will be shared externally.

This check is not an action where the administrator copies the file to move it to another site. It is first a process to distinguish whether the same file is being viewed on Teams and SharePoint screens. If it is the same file, modifications or deletions on one side will be reflected on the other screen, so do not delete the original for testing purposes.

Whether a new team is needed or a channel is needed

A new team is suitable when separate member boundaries, owners, and a site are required. If the same members work together and only the topic is divided, adding standard channels to an existing team may simplify management. If a space visible to only certain people is needed, consider a private channel, but keep in mind that a separate site and permission management will be required. For shared channels, review external collaboration requirements and organizational policies as well.

If the file opens but the team is not visible, or vice versa

• Only the site file opens: Check whether you have direct permission to the link or the site of that file. Site access and team membership registration are not the same.
• You can see the team but there is no specific channel: Check if you are included as a member of private or shared channels. Being a team owner does not automatically give you access to all private conversations and files like a regular member.
• Channels are visible but file access fails: Compare the account/organization with the actual site, and check SharePoint sharing restrictions, policies, and permission synchronization status.
• Former employees can still access files: Investigate whether separate site permissions or file links remain outside of team membership. Do not consider access revocation complete after checking only one membership list.

Do not attempt to solve the problem by making the entire site public or creating a new site to copy content. Member issues should be resolved in Teams owner/member management, and content sharing issues should be addressed in SharePoint permissions and sharing scope according to the cause.

Before deleting a team or changing its group, check the effects on connected mail, calendars, sites and files. Resources that are not visible on the current screen may still be linked. To remove one person, change the relevant membership or access rather than deleting the team. When a project ends, first decide who will take ownership, which records must be retained and whether to archive the team. Tidying the Teams interface and deleting connected data are different operations.