CMA Written Estimates for Vets: The £500 Rule Explained

When you must give a written estimate

Under the CMA's veterinary-sector reforms, your practice must give a pet owner a written estimate whenever the treatment a vet recommends is reasonably likely to cost £500 or more, including VAT. If the likely total then rises by 20% or £500 — whichever is lower — you must give the owner an updated written estimate. The threshold is about the recommended treatment pathway, not a single line item, so a course of treatment that crosses £500 in total triggers the requirement even if no individual element does.

That is the rule in one paragraph. The rest of this guide covers what counts toward the threshold, when the update obligation bites, and how to make the process reliable rather than something the team has to remember case by case.

What the CMA actually requires

The CMA's guidance for practices is specific about both the threshold and the trigger for an update. On the initial estimate, it states that you must "Give the pet owner a written estimate which indicates the reasonably likely costs of the treatment pathway which the veterinary professional ... recommends, if those costs are reasonably likely to be £500 or more including VAT."

On the update obligation, the guidance requires you to "Give the pet owner a further written update if the total estimated cost of the treatment pathway is reasonably likely to increase by 20% or £500 including VAT (whichever is lower)."

Three things are worth drawing out of that wording:

• "Including VAT" is explicit. The threshold is the price the owner pays, not the ex-VAT figure. A treatment quoted internally at £430 plus VAT is over the line.
• "Treatment pathway" means the recommended course of care, not a procedure code. Diagnostics, the procedure, medication, and follow-up that the vet is recommending together count toward the £500.
• "Reasonably likely" sets the test at the point of recommendation, using the clinician's judgment. It does not require certainty — it requires a genuine estimate of the likely cost.

When the update obligation bites

The "20% or £500, whichever is lower" wording is where practices will most easily slip. The point at which you owe an updated estimate depends on the size of the original:

• On a £600 estimate, 20% is £120 — lower than £500 — so an update is owed once the likely cost rises by £120, to around £720.
• On a £3,000 estimate, 20% is £600 — higher than £500 — so the lower figure governs, and an update is owed once the likely cost rises by £500, to around £3,500.

The practical effect: on smaller estimates the percentage trigger applies; on larger ones the flat £500 trigger applies. Either way the obligation is to put the revised figure in writing before the extra cost is incurred, so the owner can make an informed decision.

Building the £500 rule into clinical workflow

The compliance risk here is not understanding the rule — it is catching it consistently in a busy consult. A process that depends on a clinician remembering the threshold mid-appointment will fail audit. A few controls make it reliable:

1. Estimate at the point of recommendation. Generate the written estimate when the vet recommends the pathway, not at checkout. The CMA's test is set at the recommendation stage.
2. Make the threshold a system prompt, not a memory test. If your practice management system can flag when an estimate reaches £500 including VAT, use it. If not, a desk-level rule ("any recommended pathway over £500 gets a written estimate before it starts") covers it.
3. Capture the estimate on the clinical record. Keep the written estimate, the date, and the owner's acknowledgement. This is the evidence that the obligation was met.
4. Define the re-estimate trigger. Give the team the "20% or £500, whichever is lower" rule as a one-line decision aid, and a route to issue the updated estimate quickly when scope changes mid-treatment.
5. Write the SOP. Fold the estimate process into your SOP framework so it is documented, version-controlled, and trainable for new staff.

Common gaps to close

• VAT ignored. Estimating on ex-VAT figures pushes some pathways under the threshold on paper but over it in reality. Estimate on the VAT-inclusive total.
• Pathway split into parts. Quoting diagnostics, procedure, and medication separately so none individually hits £500 does not avoid the rule — the test is the recommended pathway's total likely cost.
• No update process. Practices put effort into the first estimate and none into the update. The 20%/£500 trigger is a live obligation throughout the treatment, not a one-off at the start.
• Verbal only. A spoken figure is not a written estimate. The requirement is explicitly for it in writing.

How estimates fit the wider CMA package

The written-estimate rule is one of several CMA remedies a practice has to operationalise together. It sits alongside published price lists, prescription fee caps, ownership disclosure, and a documented complaints process. Sequencing all of them is what the CMA preparation timeline is for, and the CMA compliance self-assessment tool flags which of them your practice still has open. Treated as one workstream within your clinical governance framework — rather than five separate scrambles — the package is manageable for an independent practice.

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This guide reflects the CMA's published guidance for veterinary businesses as of June 2026. It is general compliance information, not legal advice. The binding detail will be set out in the CMA Orders. Verify the current position against the CMA's guidance for veterinary businesses and consult your defence body for practice-specific advice.