Assumption Log

Assumptions are factors in the planning process that are considered to be true, real, or certain, without proof or demonstration. Constraints are also documented in this log. Constraints are limiting factors that affect the execution of the project. Typical constraints include a predetermined budget or fixed milestones for deliverables. Information in the assumption log includes:

Assumptions can come from any document in the project. They can also be determined by the project team. Constraints may be documented in the project charter and are determined by the customer, sponsor, or regulatory agencies.


The assumption log provides information to:

  • Requirements documentation
  • Project scope statement
  • Network diagram
  • Duration estimates
  • Project schedule
  • Quality management plan
  • Resource estimates
  • Risk register
  • Stakeholder engagement plan

The assumption log is an output from the process 4.1 Develop Project Charter in the PMBOK® Guide – Sixth Edition. This log is a dynamic document that is updated throughout the project. Assumptions are progressively elaborated throughout the project and are eventually validated and no longer assumptions.


Tailoring tips

Consider the following tips to help you tailor the assumption log to meet your needs:

  • Combine the assumption log with the issue register and the decision log, to create an AID Log (A = assumption, I = issue, D = decision). You can create them in a spreadsheet with each sheet dedicated to either assumptions, issues, or decisions.
  • If you have a very large project you may want to keep the constraints in a separate log from the assumptions.


The assumption log should be aligned and consistent with the following documents:

  • Project charter
  • Issue log
  • Risk register
Document element  Description 
ID Identifier
Category The category of the assumption or constraint
Assumption/constraint A description of the assumption or constraint 
Responsible party The person who is tasked with following up on the assumption to validate if it is true or not
Due date The date by which the assumption needs to be validated
Actions Actions that need to be taken to validate assumptions
Status The status of the assumptions, such as active, transferred, or closed
Comments Any additional information regarding the assumption or constraint