Comparing Australia’s biggest health insurers: complaints, gap costs and discounts

Australia has more than 40 private health insurers, yet most people can name only a handful. That familiarity isn’t accidental: the market is highly concentrated, with about eight in 10 health insurance policies held by the five biggest funds. Two brands—Medibank and Bupa—dominate, together accounting for more than half of the market share.

Size, however, doesn’t automatically translate to better value. Large funds can offer some policies that represent poor value, while still having other policies that are worth considering. At the same time, some smaller insurers—despite holding less than 0.5% market share—can be competitive and provide strong cover at comparatively low premiums. For consumers, the challenge is less about choosing “big versus small” and more about understanding the trade-offs within each fund and each policy.

This article focuses on the “big five” health funds—Medibank, Bupa, HBF, HCF and NIB—and compares them using the factual points available: complaints ratings, out-of-pocket (gap) costs, common discounts and policy features that matter to families and young adults. The aim is not to declare a single winner, but to help you narrow your shortlist and ask better questions before you sign up or switch.

Why the big five matter—and why the details still matter more

Because such a large share of Australians are insured with the biggest funds, even small differences in policy design, gap arrangements, or discount structures can affect a lot of households. Yet it’s also important to remember that “the fund” is not the same thing as “the policy.” A large insurer may have a mix of excellent and poor-value products, and the best choice for you will depend on your budget, the level of hospital cover you want, and how you use extras and hospital services.

One practical takeaway: treat the fund name as a starting point, not a conclusion. When comparing, look for measurable indicators—such as complaints performance and gap protection—and then drill down into the specific policy that fits your needs.

Complaints: what “Medium” means for the big five

One way to assess how an insurer behaves in the real world is to look at complaints and serious disputes handled by the Private Health Insurance Ombudsman. Based on the available information, all of the big five funds are currently rated Medium for complaints.

That doesn’t mean they receive the same number of complaints in raw terms. Larger funds naturally have more members, and a bigger customer base can generate more complaints. To avoid automatically penalising large insurers simply for being large, the complaints rating takes the size of the fund into account. Ratings are categorised as Low, Medium or High, with Low being better because it indicates fewer complaints and fewer serious disputes relative to the insurer’s size.

It is also notable that only a small group of insurers are currently rated Low for complaints: ACA, Hunter Health, Health Partners, Mildura and St Lukes. While this article focuses on the big five, that list is a reminder that smaller funds can sometimes outperform larger competitors on certain consumer experience measures.

• Big five complaints rating: All rated Medium.
• How it’s measured: Complaints and serious disputes handled by the Ombudsman, adjusted for fund size.
• What to do with this: Use it as a screening tool, then compare policies and costs in detail.

Out-of-pocket costs: understanding “gap” and why it varies by state

For many members, the most frustrating surprise in private health insurance is the “gap”—the out-of-pocket cost you pay for treatment even when you have hospital cover. Funds can reduce this risk through agreements with particular doctors and hospitals, and by offering arrangements that increase the likelihood that members pay either no gap or a known (capped) gap.

To compare insurers on this issue, funds can be assessed using a “gap rating,” which reflects how likely members are to be left out of pocket. A higher gap rating is better. Importantly, gap ratings are calculated on a state and territory basis, because the share of services that attract out-of-pocket costs can vary by location and by the local mix of providers and agreements.

The ratings are based on the percentage of procedures in hospitals where members paid out-of-pocket costs (the gap payment). The assessment considers the percentage of services where members either paid no gap or a known gap, compared with the state average.

Which big funds perform best on gap protection?

Among the big five, Bupa and HBF stand out for lower out-of-pocket costs. They offer at least average gap protection in all states and above-average protection in one or more states. By contrast, the other big funds have below-average or worse gap protection in some states.

This doesn’t mean that every member of Bupa or HBF will always avoid out-of-pocket costs, or that members of other funds will always pay more. It means that, based on the available measure, Bupa and HBF are more likely than the state average to deliver services where members pay no gap or a known gap, and they do so consistently across all states.

• Best for gap protection (among the big five): Bupa and HBF.
• Why: At least average gap protection in all states; above average in one or more states.
• Watch-out: Other big funds can have below-average or worse gap protection in some states.

Discounts and premium timing: what’s commonly available

Premiums matter, but discounts can be complicated—especially when they depend on payment method, membership type, or eligibility through an organisation. The big five share some common approaches, and a couple of funds offer specific payment-related discounts.

First, all health funds allow members to prepay their annual premium before 1 April each year to avoid the premium increase—at least until the following year. For households that can afford to pay upfront, this can be a straightforward way to manage cost increases, though it requires cash flow planning.

Second, HBF and NIB offer a 4% discount if you pay by direct deposit. In addition, HBF offers an extra 3.83% discount for prepaying your annual premium on some policies. Combined, that can mean a possible total discount of 7.84% for eligible HBF members using both approaches.

Third, all the big funds have discount agreements with companies or organisations such as super funds, associations and clubs, or banks. These arrangements can be easy to miss, especially if you don’t realise your workplace, professional association or financial institution has a deal in place. The practical advice is simple: ask your insurer what discounts are available and whether you qualify.

• Prepay before 1 April: Available across all funds to avoid the upcoming premium increase until the next year.
• Direct deposit discount: HBF and NIB offer 4%.
• Extra prepay discount (some policies): HBF offers an additional 3.83% (potential total 7.84%).
• Organisation-based discounts: Common across the big funds; eligibility varies.

Families and dependants: how “free kids” and age limits work

Family pricing can be one of the most valuable features in private health insurance. Under typical arrangements, families pay the same premiums as couples, which means children are insured at no additional premium cost.

Rules for adult children have also shifted in recent years. In 2021, the government increased the age cap for adult children on their parents’ policy from 24 to 31. At the same time, the age limit was removed for dependants living with disability (NDIS participants).

However, these changes are not mandatory for private health funds. Insurers can set different age limits. One fund may allow young adults on family policies up to age 28, while another may allow them to remain covered up to their 32nd birthday. That variation means you should confirm the exact rules with your insurer rather than assuming the same age cut-off applies everywhere.

Even when adult children can remain on a family policy, there are usually conditions. These can include requirements that the child is not married or in a de facto relationship, that they are financially dependent on the policyholder, and that they stay under certain income limits.

Cost is another key factor. While children and full-time students up to age 31 can often stay on a regular family policy for free, keeping older dependants and non-students covered usually involves an additional cost. Depending on the insurer, this can add up to 30% to your premium.

As a general decision point, it often makes sense to keep adult children on your policy while there’s no extra cost. Once there is an added premium, it is worth reconsidering whether their needs still match yours. A parent might want a Silver, Silver Plus or Gold policy, while an adult child may be better suited to Bronze cover, extras-only, or potentially no private health insurance—depending on their circumstances and preferences.

Young adult discounts: what Medibank, Bupa and NIB offer

For people joining hospital cover before they turn 30, discounts can make a noticeable difference. Medibank, Bupa and NIB offer discounts to new customers who sign up before age 30.

The structure is age-based: you can get 2% off your premium for every year you’re below 30, up to a maximum of 10% for people aged 18–25. If you stay on that policy, you keep the full discount until you turn 41.

These funds also allow members to keep the discount if they switch cover. They also allow you to carry across a discount if you currently hold one with another fund and switch to them. For younger members considering a move, portability of the discount can be an important detail to confirm during the quoting process.

• Funds offering under-30 discounts: Medibank, Bupa, NIB.
• Discount rate: 2% per year under 30, up to 10% (ages 18–25).
• How long it lasts: Keep the full discount until age 41 if you stay on the policy.
• Switching: Discount can be retained when switching cover; can be recognised when switching from another fund.

Not-for-profit versus for-profit: what the big five look like

Some consumers care whether their insurer is run on a not-for-profit basis. Among the large funds, HBF and HCF are the only two that are nonprofit.

Medibank and NIB are listed on the stock exchange and pay dividends to shareholders. Bupa is described as for-profit, but it is part of the international Bupa Group that is nonprofit.

Ownership structure doesn’t, by itself, tell you whether a given policy is good value for you. But it can be a relevant factor for people who prefer a particular type of organisation, or who want to understand where profits may flow.

How to use these comparisons when shopping for cover

The big five are familiar names, but the most useful comparisons are the ones that connect directly to your experience: the likelihood of out-of-pocket costs, the presence of discounts you can actually access, and the rules that affect your family’s eligibility and price.

Based on the information available, a reasonable approach is to treat complaints ratings as a baseline (all big five are Medium), then pay closer attention to gap protection—especially if you are concerned about unexpected bills after treatment. In that area, Bupa and HBF appear stronger across states. After that, look at premium management options such as prepaying before 1 April, and check whether you qualify for direct-deposit discounts or organisation-based deals.

For families, confirm the dependant rules in writing: age limits, student requirements, relationship status rules and income thresholds can all matter. For young adults, the under-30 discount structure offered by Medibank, Bupa and NIB can be significant, particularly because it can be retained until age 41 if you stay on the policy.

Questions to ask your insurer before you join or switch

• What is my fund’s gap protection like in my state or territory, and how often do members pay no gap or a known gap?
• Do you have agreements with particular doctors and hospitals that reduce out-of-pocket costs for common procedures?
• Can I prepay before 1 April to avoid the annual premium increase until the following year?
• Do I qualify for a discount through my employer, super fund, association, club or bank?
• If I pay by direct deposit, is there a discount (and does it apply to my policy)?
• If I’m under 30, do I qualify for an age-based discount, and can I keep it if I change cover later?
• For family cover, what are the exact rules for adult dependants—age limits, student status, income limits and relationship status?
• If an adult dependant no longer qualifies to stay free on the policy, what is the additional premium (and could it be up to 30%)?

Ultimately, the most reliable way to compare health insurance is to match the policy to your likely usage and tolerance for out-of-pocket costs, then layer in the discounts and eligibility rules that apply to your household. The big five may dominate the market, but the best decision still comes down to the fine print—and to asking the right questions before you commit.