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Foundation · 2 min read

Schedule basis memorandum

Document the planning rules, assumptions, calendars, coding, logic, resources, constraints, and calculation settings behind the schedule.

Working definition

A native schedule file shows what was entered; a schedule basis memorandum explains why. It allows another professional to understand the execution strategy, reproduce the calculation, identify deliberate exceptions, and distinguish approved assumptions from accidental software defaults.

Key takeaways

  • The schedule basis explains why the native file is structured and calculated as it is.
  • Document both organization standards and project-specific exceptions.
  • Version the basis and reconcile it with every approved material change.
01

Minimum professional content

Cover scope and WBS, schedule levels, activity naming and coding, calendars and time units, duration basis, logic strategy, constraints and milestones, resources and costs, risk and contingency, progress measurement, calculation options, quality thresholds, baseline control, updates, change control, reporting, and file governance.

02

Keep it synchronized

Update the memorandum when a material planning rule changes, but preserve prior approved versions. The current schedule, narrative, basis, and change register should tell one consistent story.

Produce a review-ready schedule basis

Draft the basis alongside the baseline rather than reconstructing it after approval.

Before you start

  • Contract schedule specification
  • Execution plan and WBS
  • Calendar and coding standards
  • P6 calculation settings

  1. Define purpose and hierarchy

    State schedule purpose, level, project boundaries, WBS, responsibility, and connections to external schedules.

    Verify: Scope and control levels reconcile with contract and management documents.

  2. Document modeling rules

    Explain activity naming, duration basis, calendars, logic, lags, constraints, codes, resources, costs, and percent-complete rules.

    Verify: Every deliberate exception is identifiable and justified.

  3. Record calculation and quality rules

    List data-date practice, scheduling options, critical-path method, float basis, path settings, and quality thresholds.

    Verify: A second scheduler can reproduce the calculation.

  4. Define control processes

    Describe baseline approval, update cycle, change control, recovery, risk, reports, file exchange, naming, and retention.

    Verify: Each process has an owner, input, output, and approval point.

  5. Review and issue

    Reconcile the memorandum with the final native schedule and obtain named approval.

    Verify: Version, date, approver, and corresponding schedule checksum are recorded.

    Field-ready control

    Schedule basis contents

    • Scope and WBS
    • Calendar and time units
    • Activity and code rules
    • Duration and resource basis
    • Logic, lag, and constraint rules
    • Data date and P6 options
    • Quality thresholds
    • Baseline and change control
    • Update and reporting cycle
    • Risk and contingency
    • File naming, exchange, and retention
    • Approval and schedule checksum

    Common questions

    Is a schedule narrative the same as a schedule basis?

    No. The basis records enduring planning and control rules; the update narrative explains what happened and changed during a reporting period.

    Sources and scope

    Follow the reference trail.

    This guide is original educational commentary. Kairos reference records identify the source organizations, editions and scope behind this guidance. The original publishers retain their publications and rights.

    Schedule Assessment Guide: Best Practices for Project SchedulesU.S. Government Accountability Office · checked 2026-08-01UFGS 01 32 01.00 10: Project ScheduleWhole Building Design Guide / U.S. Department of Defense · checked 2026-08-01Recommended PracticesAACE International · checked 2026-08-01