AMC vs CMC for lab equipment: which contract to sign
The difference between an AMC and a CMC for diagnostic lab instruments, what each one excludes, and when comprehensive cover is actually worth its price.
Last reviewed 5 August 2026
The quotation arrives with two numbers on it, one roughly twice the other, and a renewal date that is closer than you would like. The decision looks like a budget question. It is really a question about which failures you can absorb without disrupting reporting.
The actual difference
Both contracts buy you the same scheduled preventive visits and the same engineer when something stops. The difference is parts.
| What you get | AMC | CMC |
|---|---|---|
| Scheduled preventive visits | Yes | Yes |
| Engineer's labour on a breakdown | Yes | Yes |
| Spare parts | Charged separately, often at list price | Included |
| Consumables (probes, lamps, tubing, filters) | Usually charged | Usually included — check the wording |
| Major assemblies (optics, pumps, boards) | Charged, and these are the expensive ones | Included, subject to exclusions |
| Software and firmware updates | Varies | Usually included |
| Typical annual cost | 4–8% of instrument value | 8–15% of instrument value |
| Where the risk sits | With the lab | With the vendor |
Cost bands are what Indian diagnostic labs commonly see for mid-range analysers. Treat them as a sense-check on a quotation, not a benchmark to negotiate against — they vary widely by manufacturer, instrument age and city.
How to decide, per instrument
Not per lab. The right answer is usually a mix, and the questions are these:
What does one bad failure cost?
Ask the vendor for the price of the three most commonly replaced major parts. If any single one approaches the annual difference between AMC and CMC, the comprehensive contract is reasonably priced insurance. If the expensive parts almost never fail on that model, you are paying a premium for a risk that is not there.
What happens to the lab when it stops?
An instrument with no backup, whose failure means samples go out to a referral lab or patients are asked to come back, is worth covering comprehensively even when the arithmetic is marginal. The cost of downtime rarely appears in the quotation, and it is usually the larger number. If you already record downtime per instrument, this stops being a guess.
How old is it?
Failure rates rise as instruments age, which is exactly when vendors start declining comprehensive cover or pricing it steeply. An instrument in years one to three often does not need CMC; the same instrument in year seven may not be offered it. If a vendor will not quote CMC on an instrument, that is information about its reliability — treat it as a signal about replacement, not just about contracts.
Can you actually get the part?
For an older model, ask directly whether spares are still manufactured and what the lead time is. A comprehensive contract that includes a part nobody can supply for six weeks does not keep you reporting. Where lead times are long, response-time commitments and loaner arrangements matter more than the parts clause.
The clause labs under-negotiate
Price gets the attention; response time decides whether the contract helps you. Two numbers are worth arguing over and getting in writing:
- Response time— how long until an engineer makes contact and is on site. “Best effort” is not a commitment.
- Resolution or uptime commitment — a guaranteed percentage of uptime, or a standby instrument if repair passes an agreed number of days.
Vendors will often concede on response time more readily than on price, and for a critical analyser that is the better win. If you are tracking how long past breakdowns actually took to close, bring that record to the negotiation — a vendor whose average response was four days against a promised twenty-four hours has a hard time defending a renewal increase.
Do not let one lapse
A lapsed contract is the expensive kind of quiet failure. Nothing breaks on the expiry date; it breaks two months later, and the visit that would have been covered arrives as a quotation. Renewal dates need to be somewhere that warns you sixty days out — not a calendar entry belonging to one person.
This is also a records question. Contract type, provider, value and end date are part of what a lab is expected to be able to show for each instrument, and an assessor asking how you assure continuity of service on a critical analyser is asking about exactly this.
Common questions
What is the difference between AMC and CMC?
An annual maintenance contract (AMC) covers the engineer's visits and labour but bills spare parts separately. A comprehensive maintenance contract (CMC) covers labour and parts together for one fixed fee. The scheduled maintenance is usually identical; what differs is who pays when something breaks.
Is CMC worth the extra cost?
It depends on the cost of the parts that realistically fail. On an instrument where a single failure — an optical bench, a syringe pump, a main board — costs more than several years of the price difference, CMC is buying predictability at a fair price. On a simple instrument with cheap parts, AMC plus a repair budget usually costs less over five years.
What is normally excluded even from a comprehensive contract?
Almost always: consumables and reagents, damage from power fluctuation or water ingress, damage from misuse or unauthorised repair, glassware and accessories, relocation, and anything after the instrument passes an end-of-support date. Read the exclusions before comparing prices — two CMCs at different prices are often not the same contract.
When should we start renewal discussions?
Sixty days before expiry, and ninety for an instrument you may want to renegotiate or replace. A contract that lapses converts your next service call into a chargeable visit at the worst moment, and vendors have little reason to backdate cover.