Define: Temporarily out of service (TOS)
In a contract, Temporarily out of service (TOS) refers to a planned, scheduled interruption of a system, service, or piece of equipment for a defined period, such as during maintenance, upgrades, or repairs. It distinguishes a controlled, agreed pause from an unplanned outage or breach, often triggering notice obligations and exclusions from downtime or service level calculations.
Legal accuracy standard set & glossary spot-checked by Imad Mohammed Nazar , Skadden-trained M&A lawyer, Legal Engineer at GenieAI
What Temporarily out of service (TOS) Means in a Contract
Temporarily out of service (TOS) describes a deliberate, planned cessation of a system's, service's, or asset's normal operation for a set or estimated period. Unlike an accidental failure or an emergency shutdown, TOS is typically anticipated, scheduled, and communicated in advance under the terms of the agreement. It is a status label used to signal that the provider or operator has intentionally paused functionality, usually for a legitimate operational reason such as maintenance, testing, upgrades, or safety inspections.
The concept matters because contracts often distinguish between outages that count against a provider's performance obligations and those that do not. When a system is properly designated as temporarily out of service under agreed procedures, the downtime is frequently excluded from service credits, penalties, or breach determinations, provided the party followed the correct notice and process requirements set out in the contract.
This term commonly appears alongside related concepts such as scheduled maintenance windows, force majeure, and business continuity provisions, and it interacts closely with any Relevant Circumstances
Relevant Sectors