When a project schedule is copied and assigned as its own Baseline in P6 (so the Baseline project equals the Current project), why do the Baseline, Earned Value, and Forecast curves not align with each other? Should they not overlap perfectly? Where is P6 reading the Baseline data from, and what should be done to fix this?

Why Baseline, Earned Value, and Forecast Curves Don't Align After a Rebaseline in P6

This is a very common source of confusion in P6. Even when a project is copied and assigned as its own Baseline, the three curves will not necessarily overlap unless several specific conditions are met.

How P6 Calculates Each Curve:

• Baseline (BL) Curve: Drawn from the BL Project — the copied snapshot. It reflects the planned resource/cost distribution of that copied project.


• Earned Value (EV) Curve: Calculated from the Current Schedule using each activity's % Complete and the assigned Earned Value technique.


• Forecast Curve: Calculated from the Current Schedule based on remaining work projected forward from the Data Date.

Common Reasons for Misalignment:

• Data Date mismatch: This is the most common cause. If the current project's Data Date is different from the Baseline project's start or Data Date, P6 splits the curves at that point. The Forecast only begins at the current Data Date.
• Actual progress recorded: If any activities have Actual Start, Actual Units, or Actual Costs, P6 will calculate Earned Value differently from the BL planned values.
• Earned Value Technique settings: Each activity has an EV technique (e.g., Fixed Formula, % Complete, 50/50). These affect how Earned is calculated and may cause it to diverge from the BL curve.
• Resource or cost differences: If the copied project had its resource assignments modified before or after being set as a Baseline, the BL curve will differ.
• Incorrect Baseline assignment: Verify under Project > Assign Baselines that the correct project is assigned as the Project Baseline.

How to Fix It:

• Ensure the Data Date of the current schedule matches the intended baseline point (usually project start for a fresh Rebaseline).


• Confirm no activities have any Actuals recorded (Actual Start, Actual Units, Actual Costs) if the intent is a clean baseline with zero progress.


• Re-assign the Baseline via Project > Assign Baselines and confirm the correct project is selected.


• Recalculate the schedule (F9) after making any changes.


• Check the Earned Value settings under Projects > EV Settings tab to confirm the technique is appropriate.

Expected Result When Everything Is Correct:

If the current project is an exact copy of the Baseline, has no actual progress, and the Data Date is at the project start, all three curves — BL, Earned, and Forecast — should lie directly on top of each other.

Key Takeaway:
P6 reads BL data from the assigned Baseline project copy, but calculates EV and Forecast from the live current schedule using its own logic. Any difference between these sources — Data Date, Actuals, EV technique, or resource assignments — will cause the curves to diverge.