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Scheduling · Reporting · Excel

Schedule slip in days: how to report baseline vs current dates (with Excel formulas)

By PingCadence · · 6 min read

Short answer

Slip = current finish − baseline finish. In Excel that’s =C2-B2 for calendar days, or NETWORKDAYS for working days. Report three things: how many tasks finish later than baseline, the biggest slips, and which ones need a decision. Keep the baseline fixed so slips stay visible.

Three dates, three different questions

  • Baseline: the dates everyone agreed when the plan was approved. It answers “what did we commit to?”
  • Current (or forecast): today’s best estimate. It answers “when will it actually finish?”
  • Actual: what happened, once a task is done.

Slip compares the first two. The single most useful habit is to not overwrite the baseline when a date moves. Update the current date, keep the baseline, and the difference does the reporting for you.

Baseline and current bars for four example tasksDesign review now finishes 7 days later than baseline. Supplier quote is unchanged. Test fixture starts 4 days later and finishes 14 days later. Label artwork finishes 2 days early.day 0day 10day 20day 30day 40day 50Design review+7 dSupplier quote0 dTest fixture+14 dLabel artwork-2 dBaselineCurrent
Example only: grey bars are the baseline, blue bars the current forecast. The label is finish-date slip in calendar days.

Calendar days or working days?

Calendar days are what most stakeholders hear when you say “a week late”, and they’re what a due date on a contract means. Working days are what the team actually has to make up. Pick one, say which in the report heading, and don’t mix them. (Microsoft Project’s Finish Variance field is in working time, so it can disagree with a calendar-day count.)

The formulas

With task names in A, baseline finish in B and current finish in C:

Calendar-day slip (D2)

=C2-B2

Working-day slip, positive when late (E2)

=IF(C2>=B2, NETWORKDAYS(B2, C2) - 1, -(NETWORKDAYS(C2, B2) - 1))

Status label (F2)

=IF(D2>0, "Later than baseline", IF(D2<0, "Ahead of baseline", "On baseline"))

NETWORKDAYS counts both end dates, which is why there’s a −1. Add a holidays range as the third argument (NETWORKDAYS(B2, C2, Holidays!A:A)) if your team observes them. Format column D as a number, not a date, or Excel will show 7 as January 7, 1900.

TaskBaseline finishCurrent finishSlip (calendar)Status
Design reviewOct 30Nov 6+7Later than baseline
Supplier quoteNov 13Nov 130On baseline
Test fixtureNov 2Nov 16+14Later than baseline
Label artworkOct 26Oct 24−2Ahead of baseline

What goes in the status report

Most readers want three things, in this order:

  1. A count: “2 of 4 tasks finish later than baseline.” It sets the tone in one line.
  2. The biggest slips: the top three by days, each with the reason in a sentence and whether it hits a milestone.
  3. Decisions needed: the proposed new dates you haven’t accepted yet, and what you need from the reader.

Tasks finishing early are worth a line too, but don’t net them off against late ones. Two days early on one task rarely buys back fourteen days late on another.

When to re-baseline

Re-baselining resets slip to zero, so do it on purpose: after a scope change or a formally approved re-plan, never just because the numbers look bad. Keep a copy of the old baseline (Project has Baseline1–Baseline10 for exactly this) and note the date you re-baselined in the report.

Getting the current dates in the first place

The formulas are the easy part. The hard part is a current date you trust, which means asking each task owner. PingCadence asks them on a schedule you set, shows them the planned dates, collects a new date when something’s late, and keeps your original baseline, so every report shows the slip in days. How to ask for a status update covers doing it by hand.