Match the person, period and time basis
First identify the exact person and the dates being compared. Two people working at the same time are not an overlap in one person's time record. If a report only supplies durations and no start or end times, interval overlap cannot be determined from that export.
Normalize timestamps to a consistent basis while preserving their original time zone or offset. A display in local time and an export in UTC can describe the same instant differently. Do not invent a missing time zone; mark the comparison unresolved until the record's basis is known.
Check intervals that cross midnight and entries corrected after the reporting cutoff. State whether the review uses the current records or a dated reporting snapshot. Preserve record identifiers so you can distinguish an edited entry from a separate event.
Work through the fictional interval example
For one anonymous person on the same day and time basis, entry A runs from 09:00 to 10:00 and entry B runs from 09:30 to 10:30. Each lasts 60 minutes. Their recorded duration sum is 120 minutes, but their combined interval covers 90 distinct elapsed minutes.
The overlap runs from 09:30 to 10:00 and lasts 30 minutes. Entry C runs from 10:30 to 11:00 and adds 30 minutes with no overlap under the convention that an interval's end is excluded. Across A, B and C, the recorded sum is 150 minutes and the distinct elapsed coverage is 120 minutes.
These calculations identify a reconciliation question. They do not automatically determine the invoice amount. Billing may follow an agreement that uses units, a minimum charge or another authorized basis. Keep that policy decision separate from the elapsed-time calculation.
Distinguish duplicates from parallel activity
A duplicate entry may share an import identifier or an identical source record. Two entries with the same duration are not enough to prove duplication. Inspect the record identity, activity description and correction history with the person responsible for the entries.
Parallel activities need a stated reporting rule. For example, a meeting and a background deployment can overlap in clock time, but that does not automatically mean two hours of active labor occurred during one hour. The report should say what its duration measure represents.
Avoid treating an overlap as evidence of dishonesty. Keep the observation, explanation and approved correction in separate fields. A missing explanation is a reporting gap that needs review.
Review each conflict with a traceable action
The worksheet asks for the entry identifiers, original intervals, overlap duration, review state and proposed action. Use states such as awaiting clarification, duplicate confirmed, parallel work explained or correction approved. Name the reviewer and record when the decision was made.
Retain the original record or its authorized audit history when correcting an entry. Record the corrected interval, billing classification and reason. If a submitted invoice is affected, follow the organization's existing approval process rather than silently changing a historical report.
For three or more intervals, do not simply add pairwise overlaps. That can double-count a region covered by several entries. Sort intervals by start time and merge intersecting intervals when calculating distinct elapsed coverage. Keep the individual records available for interpretation.
Recalculate utilization after reconciliation
Use the billable utilization calculator only after agreeing which entries count as billable and what capacity denominator applies. A duplicate can change the numerator; approved leave can change an explicitly adjusted denominator. Those are different changes and need separate explanations.
Read the utilization formula guide for capacity definitions and the non-billable category guide for activity classification. A ratio over 100% should prompt reconciliation of scope, period, policy and records rather than a claim of extraordinary productivity.
Sources and next action
Download the time overlap review worksheet. It contains the fictional A, B and C intervals plus a blank row for your own review. Keep your original records and record any approved correction separately.
Prepared by Colabio as an original interval-accounting worksheet, checked October 6, 2026. The synthetic examples were reconciled independently: A/B union 90 minutes, three-entry union 120 minutes and total recorded duration 150 minutes. This static download does not inspect or change your time records.
MDN's date documentation explains the distinction between timestamps and local time interpretations. It does not establish a billing policy. Use Colabio time tracking and return to Colabio to carry the reviewed corrections into your actual workflow.