Mandatory Dependencies in Project Management

Understanding mandatory dependencies is crucial for effective project management and scheduling as these non-negotiable task relationships dictate the sequence of work.

This post explains what mandatory dependencies are, and provides useful tips for managing dependencies to keep your projects on track and reduce risks of project failure.

Mandatory Dependencies in Project Management

What is a Mandatory Dependency?

A mandatory dependency also referred to as hard logic refers to a relationship between two project activities or tasks where one task must be completed before the next task can begin.

These dependencies are considered mandatory because they are inherent in the nature of the work and the sequence of activities cannot be changed.

For example, when building a house, the foundation must be poured before framing and roofing can begin. The framing tasks have a mandatory dependency on the foundation work being completed first.

Mandatory dependencies impose strict order constraints that impact project schedules. If predecessor tasks are delayed, successor tasks will also be delayed. Careful planning is required when managing mandatory dependencies to avoid delays.

As a project manager, understanding where hard logic exists is key. Properly sequencing activities, building in float, and monitoring dependency paths will lead to smooth project execution.

Sources of Mandatory Dependencies

Some common sources of mandatory dependencies are:

  • Physical or Technical Constraints: Where the physical nature of the work dictates a sequence. For instance, software modules must be written before testing can begin.
  • Contractual Obligations: Required sequence spelled out in legal contracts with vendors or clients.
  • Regulatory Requirements: Government regulations mandating the order of certain activities.
  • Organizational Policies: Company procedures requiring set workflow order.

Mandatory Dependency Example

Let’s look at an example to understand mandatory dependencies further.

Imagine you are the project manager for a software development project building a new mobile app. Two key tasks in your project plan are:

  • Conduct systems integration testing
  • Release app to the marketplace

Before releasing the app to customers in the marketplace, rigorous integration testing must be completed to validate all components work together properly.

Therefore, the integration testing task has a mandatory dependency on the release task. The release cannot happen before testing confirms everything is working right.

This dependency exists due to the technical nature of software development; you cannot release untested code. It is also likely spelled out in your organizational policies and best practices that testing must precede deployment.

If your integration testing phase experienced delays, it would directly delay the market release date by the same amount of time.

As the project manager, you would need to closely monitor this dependency path and potentially bring in additional QA resources to get testing completed faster.

You may also have some buffer built into the schedule to allow for a minor delay without pushing out the release. But in general, you must recognize the hardcoded constraints created by this mandatory dependency and actively manage risks.

Understanding task relationships like this is key to keeping projects on track as mandatory dependencies create strict preprocessing and sequencing requirements that must be reflected in the project plan.

How to Manage Mandatory Dependencies

How to Manage Mandatory Dependencies

Effectively managing mandatory dependencies is key to project success. To do this, here are some tips to follow:

  • Identify all mandatory dependencies early in planning. Review predecessor/successor relationships and sequencing requirements.
  • Map dependencies in your project schedule. Use tools like Gantt charts or network diagrams to visualize dependencies.
  • Assign resources with an eye on dependencies. Make sure sufficient resources are available to complete predecessor activities on time.
  • Build in float around dependent tasks to create schedule flexibility. This helps absorb some delays.
  • Monitor dependency paths closely during project execution. Quickly identify delays that will propagate downstream.
  • Shorten dependent task durations, if possible. For example, fast-track testing activities to avoid delaying implementation.
  • Re-sequence work, if feasible, to work around hard dependencies. Some project plans can be rearranged.
  • Add resources to dependent tasks to get them done faster if warranted.
  • Communicate delays that will impact dependent activities to stakeholders.
  • Consider risk mitigation like having a contingency plan if a key dependency path runs late.
  • Manage vendor dependencies closely to ensure outsourced work is delivered on schedule.
  • Confirm completion of predecessor tasks before starting successors. Don’t assume. Verify.
  • Review lessons learned after projects to improve how you manage mandatory dependencies going forward.


Mandatory dependencies create strict order constraints in project plans that must be managed carefully.

Understanding these hardcoded sequencing relationships between tasks allows project managers to build realistic schedules, assign resources appropriately, monitor risks, and take action to avoid delays.

By identifying and mapping hard logic predecessor/successor activities and proactively managing these critical dependency paths, you can lead projects successfully from start to finish and achieve on-time delivery.

David Usifo (PSM, MBCS, PMP®)
David Usifo (PSM, MBCS, PMP®)

David Usifo is a certified project manager professional, professional Scrum Master, and a BCS certified Business Analyst with a background in product development and database management.

He enjoys using his knowledge and skills to share with aspiring and experienced project managers and product developers the core concept of value-creation through adaptive solutions.

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