Ref: A10 · Track: Agent Essentials · Time to complete: ~5 min
Why this matters
SLAs (Service Level Agreements) are the three clocks you're being measured on. They're also how Zendesk decides which tickets to put in front of you first. Understanding them keeps you out of trouble and makes your day easier.
The three SLA clocks
Every customer ticket can have up to three SLA timers running against it:
1. First Reply Time (FRT)
How long from ticket creation until your first public reply.
- Starts when the ticket is created.
- Stops when any agent sends a public reply.
- It does not restart after that — this clock is one-shot.
2. Next Reply Time (NRT)
How long from the customer's latest message until your next public reply.
- Starts every time the customer sends a new message.
- Stops every time you send a public reply.
- Runs repeatedly throughout the conversation.
3. Solve Time / Total Resolution Time
How long from ticket creation until the ticket is Solved.
- Starts when the ticket is created.
- Stops when the ticket is Solved.
- One-shot per ticket lifecycle.
What the colours mean
Next to any SLA clock on a ticket:
- 🟢 Green — you're fine.
- 🟠 Orange — you're getting close. Zendesk surfaces these tickets in SLA warning views.
- 🔴 Red — breached. The clock went past its target.
Views often sort by SLA — tickets closest to breach appear at the top. That's Zendesk telling you "work this one next".
What pauses the clock
The clocks are smart:
- Pending status pauses FRT and NRT. Waiting on the customer? Clock doesn't tick.
- On hold status also pauses (if your admin configured it to).
- Out of business hours — if SLAs are set against business hours, overnight and weekends don't count.
- Customer's timezone vs yours — SLAs respect the agent's business hours (configured on your profile).
The business-hours vs calendar-hours trap
Two kinds of SLA:
- Business hours — only counts Mon–Fri 9am–5pm (or whatever your admin set).
- Calendar hours — counts every minute, including weekends.
A 4-hour FRT in business hours is much longer wall-clock time than a 4-hour FRT in calendar hours. Don't panic on Monday morning if a ticket from Friday night looks old — if it's business hours, the weekend didn't count.
Reading the SLA badge
In the ticket sidebar, the SLA panel shows: - Which policy is active (e.g. "Standard", "VIP", "Enterprise"). - Each clock, its target, and time remaining. - When the next breach will occur.
If you think the policy is wrong, don't change it — that's an admin job. Flag it to your team lead.
Common mistakes
- Leaving a ticket Open when you're waiting on the customer. FRT/NRT keep ticking; you look late. Use Pending.
- Panicking about a red FRT when someone else already replied. Only your Group's replies count as an agent reply — check the ticket.
- Ignoring orange. Orange is the polite warning. Red costs your team its SLA numbers.
Quick check — have you got this?
- FRT clock: when does it start and when does it stop?
- You reply and set status to Pending. Is the NRT clock still running?
- A customer emails at 5:05pm. You have a 2-hour business-hour FRT. Business hours end at 5pm. When does the clock start counting?
Answers
- Starts at ticket creation, stops on your first public reply. One-shot. - No — the clock is paused while status is Pending. It resumes when the customer replies (ticket goes back to Open). - 9am the next business day. Overnight doesn't count for business-hour SLAs.Related articles
- A09 — Ticket statuses explained
- A13 — Bump-bump-solve: chasing quiet customers
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