Medical necessity — seven questions answered

What does “medically necessary” actually mean? How can the insurer decline a claim?

Every Voluntary Health Insurance Scheme (VHIS) policy contains a clause about “medical necessity” (the policy wording in Hong Kong reads “medically necessary”). Put simply, even when the bill is genuine, the doctor is real, and the hospitalisation actually happened, the insurer can still say “this service was not medically necessary” and decline the claim, or pay only part of it.

So what counts as “medically necessary”? The government’s VHIS standard template locks in five conditions, all of which must be met simultaneously:

1. The treatment must be ordered or referred by a registered medical practitioner (you cannot simply self-refer for a service);
2. It must genuinely benefit the medical condition (e.g. a brain scan for gastroenteritis would not qualify);
3. It must follow mainstream medical standards, not be done purely for convenience or comfort;
4. It must use the appropriate setting and equipment (do not admit when admission is not needed);
5. It must be at the appropriate level — safe and effective, neither excessive nor inadequate.

The key point: if any one of the five conditions is not met, the insurer can decline on “not medically necessary” grounds. Grey-area cases are most often disputed here.

My doctor approved the treatment, but the insurer says it was not necessary. What do I do?

This situation is fairly common. The doctor’s judgement and the insurer’s judgement do not always line up, because:

• The doctor focuses on the patient — what is safe, comfortable, and convenient for you;
• The insurer focuses on the policy clause — does the medical record clearly document that the service met all 5 conditions? If the documentation is not precise enough, there is room to challenge.

A few typical grey-area scenarios:

The remedy: ask your treating physician to clearly document the medical reason for every day’s care and every service in the medical record. The more detailed the documentation, the harder it is for the insurer to claim the service was not necessary.

How do I distinguish “reasonable charges” from “medical necessity”? Can both reduce my claim?

Many people conflate these two concepts, but they are actually two independent gates and can both reduce your claim:

In other words: a single claim can first be cut by “medical necessity” to remove unnecessary items, then further cut by R&C on the remaining items. With both gates stacking, a bill that looks like it should be fully paid often comes out at 60–70% of face value.

For an explanation of how R&C operates, see our Reasonable & Customary (R&C) explainer.

What is pre-approval? When should I use it?

Pre-Approval is when, before you are admitted or undergo a major procedure, your doctor or hospital submits your information and treatment plan to the insurer, and the insurer reviews and confirms in writing that “this case is medically necessary, and we will pay this amount”.

The biggest benefit of pre-approval: when you are settling the bill on discharge, the insurer cannot turn around and decline on “not medically necessary” grounds (unless your condition during surgery materially differed from what was originally submitted).

When should you use pre-approval?

• Non-emergency major surgery or large-scale treatment (e.g. knee replacement, cancer therapy);
• Cases involving more than 1–2 inpatient days;
• High-cost items where disputes are likely (e.g. robotic surgery, imported drugs).

Emergency admissions do not allow for pre-approval, but remember to notify the insurer as soon as possible after admission.

How can I reduce the risk of having my claim declined?

3 areas to focus on, from before you buy through to during the hospital stay:

Area 1: At plan selection, look for pre-approval and direct billing

Different insurers cover different hospitals through their direct billing networks. Confirm with your agent:

• “Does my plan have a pre-approval mechanism?”
• “Is the hospital I usually use, X, on the direct billing list?”
• “Which claim types is this available for? Is it optional or mandatory?”

Area 2: Before admission, communicate with your doctor proactively

Tell your treating physician: “My insurer may ask about medical necessity. Please clearly document the clinical reason for each day’s care and each service in my medical record.” A complete medical record is your strongest leverage in any subsequent conversation with the insurer.

Area 3: Do not over-medicalise

Do not admit when admission is not needed, do not repeat investigations that are not needed, do not upgrade to robotic surgery when it is not needed. Once a claim contains “obviously excessive” items, the insurer has clear grounds and it is hard to push back. Do what is medically necessary; do not add on for “convenience” or “comfort”.

My claim has already been declined. How do I appeal?

4 steps, in order:

1. Step 1

   Ask the insurer to put the reasons for declining in writing

   The Insurance Authority (IA) requires insurers to explain a declined claim in writing. A verbal “we will not pay” or a letter that just says “further details to follow” is not acceptable. Ask them to specify: which day, which item was declined, and which clause is being invoked.

2. Step 2

   Ask your treating physician for a written medical opinion

   In the letter, the doctor should explain: what the clinical observations were on each day, why the service was still medically necessary, and reference relevant medical guidelines if available. This letter is the single most important document in any subsequent appeal.

3. Step 3

   Cross-reference the policy terms line by line

   Download your plan document PDF from vhis.gov.hk and turn to the “medically necessary” section. Compare the insurer’s stated reasons to the actual clause: do they match? Is there any misreading? Quoting the original wording strengthens your position far more than relying on subjective views.

4. Step 4

   File a complaint with the Insurance Complaints Bureau (ICB)

   The ICB is an independent body whose decisions are binding on member insurers, with awards capped at HK$1,500,000 and complaints lodged free of charge.

   Official site:ICB complaints guide. Required documents: the policy, claims forms, medical reports, receipts, and the insurer’s written final response.

   Processing time: typically 4–6 months.

   Note:Before complaining to the ICB, you must first complete the insurer’s internal complaints process and receive a written final response, otherwise your case will be returned.

Why does VHIS have this clause? Does it not favour insurers?

After reading the above, it is tempting to feel “medical necessity” is the insurer’s escape hatch. But that is not quite right.

Consider the alternative: if there were no “medical necessity” gate at all, and any treatment a doctor signed off on were paid, what would happen?

• Doctors would over-investigate, choose more expensive treatments, and extend inpatient stays;
• Aggregate claims across the insurance pool would balloon;
• Insurers would have only two responses: raise premiums, or cut coverage;
• The result: every policyholder bears the cost, and those who genuinely need protection lose access to affordable options.

So the “medical necessity” gate is essentially a regulator on the system. The intent is not to favour insurers — it is to keep medical insurance sustainable over the long run, so that next year’s renewal premium remains affordable.