Setting baselines

A baseline is the plan you agreed to, frozen. Once it is set, every slip, overrun and early finish in Microsoft Project is measured against it. Set it too early and you measure against a draft. Set it too late and the record of what changed is gone. Overwrite it casually and you lose the one thing an owner most needs when a claim arrives: proof of what the original plan said. This lesson covers how Project desktop stores baselines, how to set and protect them, and how an owner should run a baseline register.

Learning outcomes

• Describe what Set Baseline copies, and how a baseline differs from an interim plan.
• Set, update and clear baselines for the whole project or selected tasks, using the roll-up options correctly.
• Read baseline variance in the Tracking Gantt, the Variance table and Project Statistics.
• Design an owner's baseline register that keeps the contract baseline intact through approved changes.

The lesson

What a baseline is in Project

Setting a baseline copies the current values of a set of fields into matching baseline fields. Microsoft describes each baseline as nearly 20 reference points in five groups: start dates, finish dates, durations, work and cost estimates [1]. In practice that means Baseline Start, Baseline Finish, Baseline Duration, Baseline Work and Baseline Cost on tasks, resources and assignments, including their timephased values, and Baseline Budget Cost and Baseline Budget Work for the budget resources from Lesson 20 [2]. After the copy, the current fields keep changing as you update the schedule. The baseline fields do not.

A project has 11 baseline slots: the unnumbered Baseline plus Baseline1 to Baseline10 [1]. It also has 10 interim plans, which are lighter: an interim plan saves only start and finish dates, into pairs such as Start1 and Finish1 [1]. Figure 1 shows the difference.

Why the unnumbered Baseline matters most

The slots are not equal. Project's variance calculations use only the unnumbered Baseline, not Baseline1 to Baseline10 [1]. The Variance table, the variance fields and the Tracking Gantt's default baseline bars all read it. Earned value can be pointed at a numbered baseline in Project Options [3], but unless you change that, it also reads the unnumbered one. So the unnumbered Baseline should always hold the current approved plan, and the numbered slots should hold the history.

Setting a baseline

Go to the Project tab, Schedule group, Set Baseline, Set Baseline [1]. In the dialog:

• Choose Set baseline and pick the slot from the list. Slots already used show the date they were last saved [4], which is the quickest way to see what you have.
• Under For, choose Entire project or Selected tasks [1].
• If you chose Selected tasks, decide on Roll up baselines: To all summary tasks pushes the new baseline values up through every summary above the selected tasks; From subtasks into selected summary task(s) recalculates the selected summaries from their subtasks, which picks up added or deleted tasks. If you selected both subtasks and their summaries, tick both [1].

Click OK. If the slot already holds data, Project asks you to confirm the overwrite [1]. Read that prompt every time. It is the only warning you get.

Adding tasks after the baseline

New tasks have no baseline values, and Project treats a blank baseline as zero, so a new task shows a variance equal to its whole cost or duration [1]. Summary tasks above it also go wrong, because their baseline no longer matches their content [1]. The fix is a selected-tasks baseline: select the new tasks, set the same slot for Selected tasks, and tick To all summary tasks. Only do this for work that is part of the approved plan, such as tasks you forgot to load. Work added by an approved change belongs in a new baseline version, as below.

Interim plans and copying between slots

Choose Set interim plan in the same dialog to save dates into a Start/Finish pair, using the Copy and Into boxes [1]. The same boxes copy one baseline into another: copying Baseline into Baseline1 copies all baseline data, while copying a baseline into an interim plan carries over only its dates [1]. That copy is how an owner archives the unnumbered Baseline before replacing it.

Clearing a baseline

Use Project, Set Baseline, Clear Baseline, choose Clear baseline plan and the slot, then Entire project or Selected tasks [5]. There is rarely a good reason to clear an owner's contract baseline. Clearing is for test runs and mistakes caught on the same day.

Reading the baseline

• Tracking Gantt (View, Gantt Chart drop-down, Tracking Gantt): each task's current bar drawn above a grey baseline bar [1][6].
• Variance table (View, Tables, Variance): Start, Finish, Baseline Start, Baseline Finish and the start and finish variances [1].
• Project Statistics (Project, Project Information, Statistics): current, baseline, actual and remaining start, finish, duration, work and cost for the whole project [1].
• Multiple Baselines Gantt (More Views): Baseline, Baseline1 and Baseline2 side by side [1].

Screenshot to come

Northgate worked example

Northgate Distribution Centre (fictional) runs on a CCDC 2-2020 stipulated price contract with Halvorsen Builders Ltd. (fictional): Contract Price $34,950,000, owner contingency $3,050,000, contract executed at M0 on Mon Jan 11, 2027, and Ready-for-Takeover / Substantial Performance targeted for Fri Jan 14, 2028 (see the Northgate fact sheet). The owner's master schedule in Microsoft Project desktop, NDC_OwnerMaster_2027-01-11.mpp, is now resource-loaded and cost-loaded from Lessons 16 to 20, with the budget resources on task 0. It is ready to baseline.

Before you click Set Baseline

The owner's scheduler runs a short checklist first, because a baseline copies mistakes as faithfully as it copies good data:

• All twelve milestones, M0 to M11, are present with the fact-sheet dates as deadlines.
• No overallocation flags on owner-controlled resources; the levelling test from Lesson 18 has been resolved or recorded.
• Construction cost ties to the $34,950,000 Contract Price; Budget Cost on task 0 shows $34,950,000 and $3,050,000.
• No manually scheduled tasks left over from drafting (Lesson 10), and the critical path runs through M9 (Lesson 11).
• A copy of the file is saved and named for the date.

The baseline register

The owner keeps the slots in a fixed pattern (Figure 2). At contract award, M0, the scheduler sets Baseline1 for the entire project and also sets the unnumbered Baseline. Baseline1 is never touched again: it is the contract award record.

Halvorsen's P6 baseline is due Wed Feb 10, 2027. When the owner accepts it, the scheduler updates the owner's master to match the accepted logic and dates, then saves Baseline2 as the accepted-GC-baseline record and sets the unnumbered Baseline again so variance now measures against the accepted plan. Baseline3 to Baseline10 stay empty until an approved change order revises time or cost. Each re-baseline follows the same two moves: save the new numbered slot, then refresh the unnumbered Baseline. The register itself, a one-page log with slot, date, reason and approval reference, lives in the project file's Notes and in the owner's document control.

Reading variance against it

Suppose, as a hypothetical for teaching only, that a monthly update shows 3.2 Slab-on-grade finishing Wed May 19 instead of Fri May 14, 2027. In the Tracking Gantt, the blue current bar now ends three working days past the grey baseline bar, and M4 Foundations and slab complete shows the same 3-day finish variance (Figure 3). Panel casting, linked start-to-start to the slab, has not moved and shows no variance. The owner's question is then the right one: which baseline date moved, by how much, and is it on the critical path to M9?

View the data

Task	Baseline Finish	Finish (hypothetical update)	Finish Variance
3.2 Slab-on-grade	Fri May 14, 2027	Wed May 19, 2027	3 days
M4 Foundations & slab complete	Fri May 14, 2027	Wed May 19, 2027	3 days
4.1 Tilt-up panel casting	Fri May 21, 2027	Fri May 21, 2027	0 days

Screenshot to come

Screenshot to come

Owner's move

• Baseline at award, and keep that copy forever. A numbered slot saved at M0 is the owner's record of the contract plan. Never overwrite it.
• Re-baseline only on an approved change. Slow progress is variance to report, not a reason to re-baseline. A new baseline follows a change order or an accepted schedule revision, with the approval recorded.
• Keep the unnumbered Baseline current and approved. Variance reads it [1]. If it holds a draft, every variance report is wrong.
• Log every save. Slot, date, reason, approval reference. The slot list shows the saved date [4], not the reason.
• Ask the contractor for the same discipline. The owner's register mirrors what the specification should require of the contractor's P6 baselines: one accepted baseline, versioned revisions, nothing overwritten.

Common mistakes

1. Baselining a draft. Setting the baseline before cost, resources and milestones are final means variance starts out wrong.
2. Re-baselining to make variance go away. The schedule looks on track and the record of slippage is lost. That record is often what decides a delay claim.
3. Adding tasks without baselining them. Each shows a variance equal to its full value, and summaries go wrong [1].
4. Using Selected tasks without a roll-up option. The subtasks update but their summaries keep the old baseline.
5. Saving history only in Baseline1 to Baseline10 and leaving Baseline blank. Variance and the Tracking Gantt read the unnumbered Baseline, so reports show zero baseline values [1].

Quick quiz

1. How many baselines can a Project desktop file hold?

   1. 5
   2. 10
   3. 11
   4. 20

2. An interim plan saves:

   1. Start and finish dates only
   2. Dates, work and cost
   3. Only cost
   4. Only the critical path

3. Which baseline do Project's variance calculations use?

   1. The most recently saved one
   2. Baseline10
   3. The unnumbered Baseline
   4. Whichever is shown in the Tracking Gantt

4. You add three missed tasks after baselining. To give them baseline values and fix their summaries, you:

   1. Clear the baseline and set it again
   2. Set the same baseline for Selected tasks with To all summary tasks ticked
   3. Set an interim plan
   4. Type the baseline dates by hand

5. In the Northgate register, what is Baseline1?

   1. The current approved plan
   2. The contract award record, never overwritten
   3. A monthly snapshot
   4. The contractor's P6 baseline file

Show answers and explanations

1. C. The unnumbered Baseline plus Baseline1 to Baseline10 [1].
2. A. Interim plans hold only start and finish dates [1].
3. C. Variance uses the initial, unnumbered Baseline only [1].
4. B. A selected-tasks baseline with the roll-up option updates the new tasks and their summaries [1].
5. B. Baseline1 is saved at M0 and kept as the permanent award record; the unnumbered Baseline carries the current approved plan.

Key terms

Baseline

A saved copy of start, finish, duration, work and cost values, used to measure variance.

Baseline slot

One of 11 storage sets: the unnumbered Baseline and Baseline1 to Baseline10.

Interim plan

A saved set of start and finish dates only, stored in Start1/Finish1 to Start10/Finish10.

Roll up baselines

Options that update summary-task baseline values when you baseline selected tasks.

Variance

The difference between a current value and its baseline value, such as Finish Variance.

Tracking Gantt

A Gantt view that draws each task's current bar above its baseline bar.

Re-baseline

Saving a new approved baseline after an approved change, while keeping earlier versions.

References

1. Microsoft. Create or update a baseline or an interim plan in Project desktop. Microsoft Support.
2. Microsoft. Baseline Budget Cost fields. Microsoft Support, Project desktop.
3. Microsoft. Application.OptionsCalculation method (Project). Microsoft Learn, Project VBA reference.
4. Microsoft. Set and save a baseline. Microsoft Support.
5. ProjectPlan365. How do I clear baseline for selected tasks? ProjectPlan365 FAQ.
6. Microsoft Project team. The many Gantt chart views. Microsoft Learn archive (Project blog).

Verified on November 6, 2026.

Next lesson in this trackStatus date and updating progress (coming soon)