What Is an Assumption?

(And Why It’s Probably Lurking in Your Plan Right Now.)

We’ve talked about Risks, Issues, and Dependencies — now it’s time for the sneakiest member of the RAID family: Assumptions.

They’re the invisible gremlins in your project plan

… the things you think are true, act like they’re true… but haven’t actually confirmed.

And yes, they’re everywhere.


🤔 What is a project assumption?

A project assumption is something you’re treating as fact — even though it hasn’t been verified.

They often sound like:

  • “The client will get back to us this week.”

  • “The budget includes final delivery costs.”

  • “We’ll have access to the staging site by Friday.”

  • “Everyone will be available during the launch window.”

Assumptions can relate to:

  • Timelines

  • Budget

  • Resources

  • Stakeholders

  • Access

  • Approvals

  • Team availability

Basically, anything you’re counting on.


⚠️ Why assumptions are dangerous

Assumptions seem harmless — until they aren’t.

When you build a timeline or delivery plan around something unconfirmed… and it turns out to be false?

💥 You’ve got a delay.
💥 A risk turns into an issue.
💥 Or you’re explaining to leadership why the plan just fell apart.

And the worst part? Because it was never captured explicitly, it’s hard to even explain what went wrong.


✅ What to do with project assumptions

Simple: Capture them. Question them. Review them.

Example:

Assumption: The client will provide feedback within 48 hours
Risk: If not, the project may slip by 3–5 days
Action: Set a deadline, follow up proactively, and build a buffer

You don’t have to eliminate all assumptions — that’s not realistic.

But you do need to:

  • Know they exist

  • Make them visible

  • Create contingency plans when it matters

That’s what makes your RAID log more than just admin — it’s how you protect your timeline.


🕵️‍♀️ How to spot hidden assumptions

Ask your team (and yourself):

  • What are we assuming, but haven’t confirmed?

  • What are we basing this timeline on?

  • What would derail us if it didn’t happen?

  • What do we think we know — but haven’t checked?

Most assumptions are hiding in plain sight:

  • In Slack messages

  • In casual meetings

  • In throwaway lines like “That should be fine”

If you use a good Projects, Operations & Collaboration tool, you can track all this information there. So that you don’t lose it.

🚩 “Should be fine” is almost always a red flag.


TL;DR:

  • Assumptions are unverified beliefs baked into your plan.

  • If they’re wrong, they become risks — or worse, issues.

  • Track them. Question them. Talk about them.

  • Add them to your RAID log and review them regularly.


🎯 Wrapping up the RAID Series

RAID logs aren’t just another PM checklist — they’re one of the most powerful tools in your project toolkit.

They help you:

  • Spot risks before they become issues

  • Manage issues before they escalate

  • Navigate dependencies before they block you

  • Catch assumptions before they bite

And when you use them consistently?

They give you something rare in project management: control.

So the next time someone says “a RAID log is overkill,”
Just ask them how often they find themselves firefighting.

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