Classes of Service: prioritize by risk, not by who shouts
Not every work item is worth the same, nor costs the same when it is late. Pick a prioritization policy below, schedule the deliveries and watch the value captured change in real time.
A team delivers 2 items per week, for 4 weeks. Each item has a value, and some have a deadline, with a penalty if late. Pick a prioritization policy and see how much value you capture.
Pick a policy above to run the scenario.
The four classes of service
A class of service groups items that share the same handling policy because they share the same risk and cost-of-delay profile. The four classic ones are: Standard (pays when delivered, no hard deadline), Fixed Date (has a deadline; if late, incurs a penalty or loss of value), Expedite (jumps the queue because of very high cost of delay) and Intangible (no immediate value, but important for the future, like reducing technical debt).
Making these classes explicit turns prioritization into a business decision, not a contest of who talks loudest. Each class carries a visible policy for how the work is pulled and handled.
Why FIFO wastes value
Serving in arrival order (FIFO) treats every item as equal. But when an Expedite or Fixed Date item waits behind tasks with no deadline, the team pays penalties and loses value it could have captured with the same capacity.
Prioritizing by highest value looks better, but still ignores risk: a high-value item with no deadline can push a Fixed Date item past its due date. What truly protects total value is looking at the cost of delay: how much is lost for each week of waiting.
Policies by class
The by class policy orders Expedite > Fixed Date > Standard > Intangible, ensuring deadline-sensitive items go first. The cost of delay policy goes further and orders by the financial risk of waiting.
In the lab above, those two policies capture more value than FIFO (and even more than prioritizing by value alone) because they protect exactly the items that lose value when late.
Frequently asked questions about classes of service
What are classes of service in Kanban?
They are groups of items that share the same handling policy because they have similar risk and cost-of-delay profiles. The classic ones are Standard, Fixed Date, Expedite and Intangible.
What is the Expedite class?
It is the class reserved for items with a very high cost of delay, which may jump the queue and even break WIP limits. Because it is costly to flow, it should be used sparingly.
Why not just prioritize by highest value?
Because value alone ignores risk. A high-value item with no deadline can push a Fixed Date item past its due date, generating a penalty. Cost of delay captures that risk.
What is cost of delay?
It is how much value is lost for each unit of time an item waits to be delivered. Prioritizing by cost of delay maximizes the total value captured with the available capacity.
Enjoyed learning by doing?
Take prioritization to the next level: manage a squad in the Kanban Game.
