Start from your own data
Before writing a single target, measure what you do now: median and 80th-percentile first response, and time to resolution, both in business hours. A target your team already meets 80% of the time is a target you can commit to; one plucked from a competitor's website is a target you will breach every Monday.
Choose the targets
Most desks need three: first response (how long until a human replies), next response (how long between later replies), and resolution. Set each per priority.
- Urgent: first response 1 business hour, resolution 1 business day.
- High: first response 4 business hours, resolution 2 business days.
- Normal: first response 8 business hours, resolution 5 business days.
- Low: first response 2 business days, resolution 10 business days.
Define business hours properly
Each team that works a different pattern needs its own calendar: weekly opening hours, public holidays, and a named time zone. Store hours as local times in that zone - never as fixed UTC instants - or every deadline shifts by an hour when daylight saving changes.
Express targets in hours, not days. A "day" is ambiguous when a business day is nine hours long.
Decide when the clock pauses
The clock should pause only when the next move belongs to the customer. Waiting on another internal team is still your delay; waiting on an approver is still your delay. If those pause the clock, the report will look excellent while customers wait.
Two edge cases matter. A ticket already overdue when it is parked should stay breached. And a ticket resolved late stays breached - finishing the work does not undo the miss.
Escalate before the breach, once
Warn the assignee at around 80% of a target, notify the team lead at 100%, and reassign or raise priority if it runs well past. Make sure each escalation fires exactly once per ticket - a lead who receives the same alert six times stops reading them.
Different customers, different targets
Premium customers can have tighter targets by matching an SLA policy on the customer's organisation or plan tier. Keep the number of policies small; every extra policy is one more thing to explain when a customer asks why their ticket took longer.
Change policies without moving promises
When you tighten a target, apply it to new tickets. Deadlines already promised to customers should not move. If a clock genuinely needs resetting, make it a deliberate action with a reason, by someone allowed to do it.
Report attainment honestly
SLA attainment should answer: of the promises made in this period, how many were kept? Count clocks by when they started, treat running clocks as neither met nor breached, and show an empty period as empty rather than 100%.