A service level agreement (SLA) in field service is a written commitment to respond to and resolve a customer's service requests within defined times, usually with priority tiers and consequences if you miss. The SLAs that work are the ones built backward from your crew's real travel times and capacity, not forward from what the customer asked for.
SLAs are mostly a commercial work feature. Property managers, facilities teams, restaurant groups and healthcare sites want to know that a down rooftop unit or a failed walk-in cooler gets attention within hours, not "sometime this week." Winning that work means signing a promise. Keeping it means your schedule has to be built around it.
This guide covers what goes into an SLA, how to set the numbers, and how to measure compliance. It's practice guidance, not legal advice. Have an attorney review any contract you sign. For how SLAs fit with the rest of the operation, see the field service management guide.
What a field service SLA actually defines
Every SLA, however formal, answers the same five questions.
1. What counts as the start of the clock?
Usually the moment a request is received: a call, an email, a portal ticket. Define it precisely. "Received" at 4:55 p.m. on a Friday is a different promise if the clock runs on business hours versus calendar hours.
2. What is response time?
Response time is how long until you do something. Depending on the contract, that can mean:
- Acknowledgment: someone confirms the request was received.
- Remote response: a technician calls to triage.
- On-site arrival: a technician physically arrives.
These are very different promises. A four-hour acknowledgment costs almost nothing. A four-hour on-site arrival requires a technician who can drop what they're doing and drive there. Write which one you mean.
3. What is resolution time?
Resolution time is how long until the problem is fixed or a temporary fix restores service. Resolution is harder to promise because it depends on diagnosis and parts. Many SLAs define resolution as "restored to operation" with a separate, longer window for the permanent repair.
4. What are the priority tiers?
Not every request is an emergency. A typical structure:
| Priority | Example | On-site response | Resolution target |
|---|---|---|---|
| P1 Critical | No heat in occupied building, cooler failure with product at risk | 4 hours | 24 hours |
| P2 High | Partial system failure, one unit down of several | Next business day | 3 business days |
| P3 Routine | Noise, minor leak, non-urgent repair | 3 business days | 10 business days |
| PM | Scheduled maintenance | Within agreed window | Per schedule |
These times are illustrative. Yours should come from your own travel and capacity numbers, covered below.
5. What happens if you miss?
Consequences range from nothing (a "target") to service credits, fee reductions or termination rights. The stronger the penalty, the more conservative your promised times should be.
Setting SLA times you can keep
The mistake most companies make is starting with the customer's request and agreeing to it. Start with your crew instead.
Step 1: Map the travel
For a P1 on-site promise, the binding constraint is usually the drive. Take the customer's site and ask: from where my technicians typically are during the day, how long does it take to get there at the worst realistic time? Not from the shop. From the job they'll most likely be on.
Worst-case response = time to finish or pause current job + drive from current job + buffer
Forty minutes of margin is thin. If the site is at the edge of your service area, a four-hour P1 may be a promise you'll break on the first busy day.
Step 2: Count the capacity you must hold
An on-site SLA means some capacity is always on call. If you have ten SLA customers and each might raise one P1 in a week, you need enough slack each day to absorb those calls without blowing up the rest of the schedule.
A rough planning figure:
Reserved hours per day = expected P1 calls per day × (average job hours + average drive hours)
Hold that time open on the technicians who cover SLA customers, or plan explicitly which non-SLA jobs get bumped when a P1 lands. The capacity planning guide shows how to build this into a weekly plan, and the glossary entry on emergency call scheduling covers the day-of mechanics.
Step 3: Account for skills and parts
A response is only useful if the technician who arrives can fix the problem. If only two technicians are certified for a customer's equipment, the SLA is really a promise about those two people's availability. For resolution times, check whether the common failure parts are stocked. The inventory management guide covers how to decide what rides on the truck.
Step 4: Price the promise
SLA coverage costs you idle capacity, schedule disruption and sometimes overtime. Price it accordingly. A common approach is a monthly or annual fee for coverage, separate from labor and parts on each call. The field service pricing guide covers how to build those numbers from your own costs.
Measuring SLA compliance
If you sign SLAs, you need to measure them more carefully than the customer does. Customers notice misses. They rarely notice the hits.
The core metric
SLA compliance = requests responded to within the agreed time ÷ total requests
Calculate it separately for each priority tier and each customer. A blended rate hides the P1 misses, which are the ones that end contracts.
Timestamps you need
For each request:
- Time received
- Priority assigned (and by whom)
- Time dispatched
- Time the technician arrived
- Time service was restored
- Time the permanent fix was completed
Without arrival timestamps, you're relying on memory to defend your compliance numbers. Make sure arrival is captured on site, not entered later. The work order management guide covers how to structure job records so these fields are always there.
Leading indicators
By the time compliance drops, you've already missed. Watch these instead:
- Time from received to dispatched. If this grows, the problem is in triage or dispatch, not travel.
- Average drive time on SLA calls. If this creeps up, your coverage area or technician placement is drifting.
- Share of P1 calls that bumped another job. A rising share means you need more reserved capacity.
- Reclassified priorities. If a lot of P1s are later downgraded, the triage criteria need work.
These belong in the weekly review covered in the field service reporting guide.
How SLAs change your scheduling
SLAs turn the schedule from a list of appointments into a set of commitments with deadlines. That changes how the board has to work.
Deadlines beat arrival order. A P2 received yesterday afternoon may need to go ahead of a routine job booked last week.
Location matters more. When a P1 lands, the best technician to send is usually the qualified one who will be nearest when they can break away, which depends on where their current job is. Assigning from the shop or from home addresses gives the wrong answer.
Preventive maintenance has to be fenced. PM visits are often part of the same contract. If they get bumped every time an emergency arrives, you fall behind on the PM schedule and the customer notices that too. Our preventive maintenance scheduling guide covers how to protect those visits.
Here's where scheduling software either helps or doesn't. CrewLink checks feasibility before a slot is offered, with travel computed from where the truck will actually be. For SLA work, that's the question you need answered at dispatch: who can really get there in time from where they are now.
Common SLA mistakes
Promising on-site when you meant acknowledgment. Read the exact wording. "Respond within 2 hours" can be read as arrival.
Calendar hours by accident. A 24-hour resolution on calendar hours includes nights and weekends. If you don't staff those, write business hours.
No definition of priority. If the customer gets to decide what's P1, everything is P1. Define priorities by impact with examples, and say who assigns them.
No exclusions. Severe weather, site access problems, parts on manufacturer backorder and customer-caused delays should pause the clock. List them. Have an attorney check the wording.
One SLA for every customer. A hospital and a small retail store don't need the same terms. Offer tiers. The commercial vs residential guide covers why commercial accounts behave so differently.
What to take away
- An SLA defines when the clock starts, response time, resolution time, priority tiers and consequences. Write each one precisely.
- Set response times from real drive times out of a typical job location, not from the shop, plus a buffer.
- On-site SLAs require reserved capacity. Calculate it and either hold it or plan what gets bumped.
- Measure compliance per tier and per customer from on-site timestamps. Watch dispatch delay and drive time as leading indicators.
- Price SLA coverage separately and have an attorney review the contract terms.
Common questions
What is an SLA in field service?
An SLA is a contract term that commits a service company to respond to and resolve requests within set times, usually with priority levels such as critical, high and routine. It often includes consequences, like service credits, if the targets are missed.
What is the difference between response time and resolution time?
Response time measures how long until you act on a request, which can mean acknowledging it, calling to triage or arriving on site. Resolution time measures how long until the problem is fixed or service is restored. SLAs should define both separately.
How do you calculate SLA compliance?
Divide the number of requests handled within the agreed time by the total number of requests in the period. Calculate it per priority tier and per customer, because a blended rate can hide misses on critical calls.
What is a typical SLA response time for commercial HVAC or plumbing?
There's no single standard. Terms vary by customer, equipment and location. Set your own times from measured drive times to the customer's site plus the time needed to break away from a current job, and leave a buffer.
Should a small service company offer SLAs?
It can, if the commercial work justifies it and the times are set from real travel and capacity data. Start with conservative terms, measure compliance carefully, and tighten the promises once your numbers show you can keep them.