A deadline that exists only in a task tool doesn't exist at all for half the team. People plan their day around the calendar — and if a task or meeting isn't in it, they plan without it. Getting deadlines from CTM into Outlook or Google Calendar isn't cosmetic, then. It's the difference between "I knew about it" and "nobody told me."

There are several routes and each suits a different situation. We'll go through all three — including why a downloaded .ics file stubbornly opens in an app you didn't want.

Three ways a deadline reaches your calendar

A connected account — the calendar fills itself, no clicking required
An email invitation — add the event with one click straight from your inbox
An .ics file — the universal fallback that works in every calendar

1. Connected account: the calendar fills itself

The most convenient route. You connect Google Calendar or Outlook (Microsoft 365) in your profile, and task deadlines are written to the calendar automatically — on creation and on every change.

Two things are worth knowing up front. Syncing covers tasks created or edited after connecting; older deadlines won't be backfilled until you touch those tasks. And the Outlook connection writes to calendars hosted by Microsoft — if your mail lives elsewhere and Outlook is just a program on your computer, this route won't work for you. That isn't a CTM limitation but the way Microsoft exposes calendars through its interface. Use option 2 or 3 instead; they always work.

2. Email invitation: one click from your inbox

For meetings, participants receive the invitation automatically with the notification email. Outlook renders it as a regular invite with Accept and Decline buttons, and when the meeting time changes, the next invitation overwrites the original event instead of creating a second one.

The same goes for a task with a due date: the assignee gets the assignment email with an event ready to be added to their calendar. Nothing to download, no connected account needed, and it doesn't matter where their mail is hosted.

3. The .ics file: a universal fallback

In the detail of any task or meeting you'll find two buttons — Send by email and Download .ics. The first sends the event to your own address, the second downloads the file. The .ics format is a standard that Outlook, Apple Calendar, Thunderbird and even a local Outlook profile with IMAP mail will open.

On mobile, go for the email. A downloaded file often has nothing to open it on a phone and ends up buried in the Downloads folder, while from an email the event lands in the calendar with a single tap.

Why does my .ics open in the wrong app?

A familiar scene: you download the file, double-click it — and the desktop Outlook app pops up, even though you use your calendar on the web in Microsoft 365. It isn't a fault of the browser or of the app you downloaded the file from. What opens an .ics file is decided by Windows and its file-type association.

You have three options:

Open the email in Outlook on the web. We send the event as a calendar part of the message, not as an ordinary attachment, so web Outlook offers to add it to your calendar right above the email. Nothing is downloaded and Windows never gets involved.
Change the default app in Windows. Settings → Apps → Default apps → enter .ics in the file-type field and pick an app. Web Outlook only shows up in that list if you install it from your browser as an app — both Edge and Chrome offer Install in the address bar menu.
Connect your account as described in option 1 and you'll never see the file again.

Which one to choose

On Microsoft 365 or Google Workspace and want it hands-off? Connect the account, it's a one-time setup
Team mail scattered across different providers? Rely on the email invitations — they require nothing
Need to send a date to a contractor or client? Download the .ics and attach it; it opens in anything

How CTM handles it

Google Calendar and Outlook (Microsoft 365) — automatic sync of task deadlines, part of the Pro plan
Meeting invitation by email — with Accept and Decline, updated when the time changes and withdrawn on cancellation; meetings are available from the Starter plan
Event in the task assignment email — the assignee has it in their calendar with zero setup
Send by email and Download .ics — in every task and meeting detail, regardless of plan or mail provider

Conclusion

The calendar is where people actually look. Whether you use Outlook, Google or something else entirely, there's a route from CTM into it — and when something opens in the wrong app, the answer is almost always the default app in Windows, not the tool the file came from.

Try it on your next task with a due date: open its detail and click Send by email. Within seconds the event is in your inbox and one click away from your calendar.

How to Get Tasks and Meetings into Your Calendar: Outlook, Google and .ics