For a Microsoft 365 team, connected leave management means four things: single sign-on with your work account, approved leave that appears automatically in each person's Outlook as Out of Office, a daily who's-off digest in Teams, and a read-only iCal feed so Google and Apple Calendar users see the same leave. Book Time Off includes all four at £1 per user / month.
Why Microsoft 365 teams want connected leave
Most UK small businesses already do their working day inside Microsoft 365: email and calendars in Outlook, chat and meetings in Teams, sign-in through their Microsoft work account. When leave management sits outside that, three small frictions appear and never quite go away:
- Another login. One more password to set, reset and remember, and one more account to remember to switch off when someone leaves.
- Double entry. Someone books leave in the tracker, then blocks it out in Outlook by hand so meetings are not booked over it. Two steps, and the second is the one that gets skipped.
- Another app to check. To see who is off, you open a separate tool. In practice nobody does, so a clash is only spotted when a meeting invite goes out to someone on holiday.
Connecting leave management to Microsoft 365 removes all three. Here is each piece, and what it actually does.
Single sign-on: one fewer password
Single sign-on (SSO) lets staff sign in with their existing Microsoft 365 work account instead of creating yet another username and password. Microsoft's own identity platform handles the authentication, so the leave tracker never holds a separate password to be phished or forgotten.
For a small business the practical wins are quiet but real: onboarding a new starter is faster because they sign in with the account they already have, access is tied to the Microsoft account so offboarding is cleaner, and there is one fewer credential for everyone to manage. In Book Time Off, Microsoft 365 single sign-on works for both admins and invited staff.
Outlook calendar sync
This is the piece that removes the double entry. When someone connects their Outlook, their approved leave is written into their own Outlook calendar as an Out of Office entry. Microsoft's automatic replies and Out of Office features then do what they normally do, so colleagues trying to book a meeting see that the person is away.
The important detail is the direction and the scope. In Book Time Off the sync is one way and narrow: it adds and updates that person's own approved leave and nothing else. It does not read the rest of the calendar, and it does not touch anyone else's. That keeps the Microsoft permission you grant small and the behaviour easy to predict: leave you approve shows up in Outlook, and that is all that changes.
With Book Time Off, once a person connects Outlook their approved leave is added to their calendar as Out of Office automatically, so nobody blocks holidays out by hand. The sync only adds and updates their own leave; it never reads the calendar.
→ Start free trialTeams notifications and the daily digest
The second friction, "another app to check", is solved by bringing the information into Teams, where people already are. Approved leave can be posted into a Teams channel, and a daily digest can summarise who is off that day so the team sees it in the morning without opening anything else.
In Book Time Off the digest is configurable: you choose the time it sends, it skips weekends and bank holidays, and it can greet birthdays. Crucially, it respects privacy. A leave type you have marked private posts as a generic "Off" with no reason, so a daily channel message never leaks why someone is away. Approvals themselves stay private too: a request goes to the assigned approver, never to the whole channel.
Google and Apple users: iCal feeds
Not everyone on a Microsoft team uses Outlook for everything. Some people live in Google Calendar or Apple Calendar on their phone. An iCal subscribe feed covers them in one go, without building a separate integration for each.
Book Time Off provides two read-only feeds: a personal feed of your own approved leave, and a team feed of the whole team's, each as a subscribe link that Google Calendar, Apple Calendar or Outlook can add. The link is a revocable token with no personal data in the URL, so if it is ever shared by mistake you can reset it and the old link stops working. The team feed honours leave-type privacy in the same way the Teams digest does. Because it is a one-way read feed, the calendar shows the leave but never writes back, which keeps Book Time Off the single source of truth.
What it looks like day to day
Put together, a normal week for a Microsoft 365 team looks like this:
| What happens | Where it shows up |
|---|---|
| A staff member signs in | Their Microsoft 365 work account (SSO) |
| They request leave and it is approved | Added to their Outlook as Out of Office |
| The team starts the day | A who's-off digest in the Teams channel |
| A Google or Apple user checks their phone | The same leave via the iCal feed |
| A manager wants the figures | An admin report, exported to CSV |
Nobody re-enters anything, and nobody has to remember to check a separate tool. The leave a person books flows to the places the team already looks.
Microsoft 365 single sign-on, per-user Outlook sync, a daily who's-off Teams digest and read-only iCal feeds are all included in Book Time Off at £1 per user / month. Some tools keep these for a pricier tier; here they are in the one plan.
→ Start free trialWhat it does, and does not, do
It is worth being precise, because "Microsoft integration" can mean very different things in different tools. What Book Time Off does today:
- Single sign-on with Microsoft 365 for admins and invited staff.
- Per-user Outlook sync that adds and updates each person's own approved leave as Out of Office, one way, without reading the calendar.
- Teams notifications and a daily who's-off digest into a channel, honouring leave-type privacy.
- Read-only iCal feeds (personal and team) for Google, Apple or Outlook, via a revocable link.
And, just as importantly, what it does not do, so there are no surprises: it does not read your Outlook calendar, it does not provide a two-way write-back from Google or Apple Calendar, and the iCal feeds are subscribe-only. If a feature matters to you and is not listed above, the honest Book Time Off vs Timetastic comparison sets out where each tool goes further.
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Frequently asked questions
Can staff leave appear automatically in Outlook?
Yes. With a leave tracker that syncs to Outlook, once someone connects their account their approved leave is written to their own Outlook calendar as an Out of Office entry, with no double entry. In Book Time Off the sync only adds and updates that person's own leave entries; it does not read the rest of their calendar. So the leave they book in one place shows up in Outlook without anyone retyping it.
How does a who's-off digest in Microsoft Teams work?
Approved leave can be posted into a Microsoft Teams channel, and a daily digest can summarise who is off that day so the team sees it without opening another app. In Book Time Off the digest can be sent at a chosen time, skips weekends and bank holidays, and can greet birthdays. It honours leave-type privacy too: a leave type marked private shows as a generic "Off" with no reason.
What does single sign-on with Microsoft 365 mean for leave management?
Single sign-on lets staff sign in with their existing Microsoft 365 work account instead of creating and remembering another password. For the business it means less account admin, easier onboarding and offboarding tied to the Microsoft account, and one fewer set of credentials to manage. Book Time Off supports Microsoft 365 single sign-on for both admins and invited staff.
Can Google Calendar and Apple Calendar users see the same leave?
Yes, through an iCal subscribe feed. Book Time Off provides a read-only personal feed of your own approved leave and a team feed of the whole team's, each as a revocable subscribe link that Google Calendar, Apple Calendar or Outlook can add. The team feed honours leave-type privacy, showing private types as a generic "Off". It is a one-way read feed, so the calendar shows the leave but does not write back to Book Time Off.
Do I need to be on Microsoft Teams to use it?
No. The Microsoft integrations are optional. A team that lives in Teams and Outlook gets single sign-on, Outlook sync and the Teams digest; a team that does not can still use the calendar, wallchart, approvals and the iCal feeds for Google or Apple Calendar. You turn on only the pieces that fit how your business already works.
Does connecting Outlook let the app read my calendar?
In Book Time Off, no. The Outlook sync only adds and updates that person's own approved leave entries as Out of Office; it does not read the existing calendar or anyone else's. That keeps the permission narrow and the behaviour predictable: leave you approve appears in Outlook, and nothing else is touched.