Bulk billing vs private billing calculator

Why bulk billing is a tax question, not only a billing policy

Every GP service is billed one of two ways. Bulk billed, the practice accepts the Medicare benefit as full payment and the patient pays nothing. Privately billed, the practice charges a fee, Medicare pays its benefit, and the practice keeps the difference between the fee and the benefit.

The MBS benefit is the same either way. That is the part most discussions get wrong. Moving a service from private to bulk billing does not change the Medicare component of your revenue; what changes is the gap fee, which disappears.

So the question is narrower than it first appears, and it is answerable. Is what you gain by bulk billing a service worth more than the gap fee you lose on it? What you gain is the BBPIP loading, plus whatever the payroll tax treatment of your contractor doctors does in your jurisdiction. What you lose is the gap fee on every service you convert. The two sides are measured in different units and move at different rates, which is why this needs a model rather than a rule of thumb.

What the BBPIP loading actually pays

From 1 November 2025, the Bulk Billing Practice Incentive Program pays a 12.5% loading on the MBS benefits paid for eligible GP non-referred attendance services. The loading is split 50/50 between the practice and the GP, and it is paid quarterly in arrears. MyMedicare registration is required, and registration can be backdated up to 180 days, but not before 1 November 2025.

Two details in that paragraph do more work than they appear to. The first is that the loading applies to MBS benefits paid, and that base includes the bulk billing incentives themselves. A practice that supplies its actual incentive receipts from PRODA or its practice management system will therefore see a larger loading than one that leaves them at zero. This model takes those receipts as an input and does not estimate them, because the published incentive rates vary by Modified Monash Model classification and by patient cohort, and a wrong estimate would distort the entire curve without ever looking wrong.

The second is the 50/50 split. Half of the loading is the practice's and half belongs to the GP. A model that credited the whole loading to the practice would overstate the gain by a factor of two; one that credited none of it would understate it by the same amount. The split is why this page reports the practice share and the GP share separately rather than as a single figure.

Because the loading is paid quarterly in arrears, the loading on a change you make this quarter arrives later than the gap revenue you gave up to earn it. That is a cash flow consequence rather than an annual one, but it is real for a practice with tight working capital.

Why the loading arrives all at once at 100%

BBPIP has no partial participation. To receive the loading, a practice must bulk bill every eligible service for every Medicare-eligible patient. There is no version of the program in which 80% of eligible services earns 80% of the loading.

That single design feature is why the model produces a cliff at the top of the range rather than a slope. At 99% bulk billing the loading is zero. At 100% it is 12.5% of the whole eligible base. The final percentage point of bulk billing is worth the entire loading, so converting your last private services is worth many times more per service than converting your first ones.

NSW adds a second cliff, and it points the other way. The NSW GP rebate is available only if at least 80% of GP services are bulk billed in metropolitan Sydney, or 70% elsewhere. At 79% in Sydney a practice receives nothing; at 80% it receives the full rebate. Note that this is a different test from BBPIP's: a practice can qualify for the NSW rebate while sitting well below the BBPIP threshold, and it can reach the BBPIP threshold without reaching the rebate threshold.

Averaging hides both cliffs. If you average your bulk billing rate across practitioners, across service types and across the year, you will arrive at a number that describes no decision you can actually make. The breakpoints the model reports mark where these edges fall for your own inputs, which is the only place they can be read correctly.

The gap revenue you give up, and the volume you gain back

The cost side of the decision is easier to state than the revenue side, and easier to overstate. Converting a service to bulk billing forgoes the gap fee on that service, not the whole fee, because the MBS benefit continues to be received.

The model computes the forgone amount as the volume of services not bulk billed multiplied by your average gap fee. That average is a simplification. Real practices charge different gaps for different consultation lengths, and some patients are billed at a reduced rate or not at all. If your gap structure is uneven, a single average will misrepresent the specific services you are considering converting.

There is a second effect the model deliberately does not capture, and it is the one most likely to make a real result better than the modelled one. Removing a gap fee changes patient behaviour. A practice that drops a $40 gap will typically see more attendances, shorter intervals between visits and better recall compliance, because cost was the binding constraint for some of those patients. This model holds service volume constant as the bulk billing proportion changes, so it understates the volume response to a genuine move to bulk billing. Read the curve as a comparison of the same practice under two billing policies, not as a forecast of a practice that has changed.

What bulk billing does to your payroll tax

This is the part that makes the decision state-specific, and the part practices most often miss.

Where a practice bills Medicare in its own name, retains a service fee and remits the balance to a contractor GP, the remitted amount is treated as wages for payroll tax purposes and added to the practice's staff wages for the threshold test. Two consequences follow, and they run in opposite directions to the BBPIP cliff.

First, the deemed wage is calculated on what the practice collects. A privately billed service collects the MBS benefit plus the gap fee. A bulk billed service collects the MBS benefit alone. Moving to bulk billing therefore reduces deemed wages, and in a practice already above the payroll tax threshold that reduces payroll tax. The saving is not the gap fee; it is the gap fee multiplied by the payroll tax rate, so it is real but it is a fraction of the revenue given up.

Second, the medical relief provisions in Victoria, South Australia and the ACT exempt the bulk-billed proportion of GP payments. In those states, raising your bulk billing rate raises the exempt share of deemed wages, so the relief scales with the change you are modelling. NSW is the exception that needs care: its relief is a rebate applied after tax has been assessed, not an exemption that reduces taxable wages, and that distinction matters most inside a payroll tax group, because a rebate does not change the wage base against which a group threshold is measured.

Where the decision is simpler than it looks

In four jurisdictions the payroll tax dimension drops out of the decision entirely, and it reduces to the loading measured against the gap revenue.

In Queensland the GP exemption is unconditional, with no bulk-billing condition, so a change in your bulk billing rate has no payroll tax effect at all. In Tasmania and the Northern Territory there is no medical relief, so the full payroll tax cost applies before and after: it is a constant in this decision rather than a variable. In Western Australia the relevant contract provisions are not applied to medical practices, and the assessment proceeds on the common-law character of the relationship rather than on a deemed wage.

If you are in one of those four jurisdictions, the model still runs the payroll tax arithmetic, but read the curve as a comparison of the loading against the gap. In the other four, the payroll tax line is doing real work in the result, and the state selector will change the answer.

How to read the curve

The horizontal axis is the proportion of eligible services bulk billed, from none to all. The vertical axis is practice net revenue after the forgone gap revenue and after payroll tax. The curve is plotted in one percentage point steps across the full range, with extra points placed immediately either side of each threshold so that a cliff renders as a vertical step rather than as a very steep slope.

Read your current position first, then read 100%. The difference between those two points is the answer to the question you came with. Then look for the vertical steps: those are the thresholds where a single percentage point changes the outcome by far more than the surrounding slope suggests, and they are the only places where a small change in billing policy produces a large change in revenue.

A flat curve means the two sides of the decision roughly cancel at your numbers, which is a genuine result and a common one. A curve that falls all the way to the right means bulk billing costs the practice money in your jurisdiction. A curve that rises means it makes money. Read the shape rather than the endpoint, because the endpoint alone tells you nothing about the thresholds you have to cross to reach it.

What this model does not do

It does not estimate your bulk billing incentive receipts. It takes them as an input and models them as zero when you leave them blank, which is the conservative direction. Supply the actual figures from PRODA or your practice management system so that the loading base reflects your practice rather than an assumption.

It does not determine whether your contractor arrangements create deemed wages at all. That turns on the facts of the arrangement: who controls the work, who provides the facilities, who bears the commercial risk. It is the question most likely to be disputed on review, and it is a separate analysis from this one.

It does not use the non-Medicare revenue figure you enter. Whether revenue from WorkCover, insurers or cosmetic work affects BBPIP eligibility is unpublished, so the amount is recorded, restated in the assumptions, and applied to no figure. Do not read the curve as having taken it into account.

It does not model the volume response to removing a gap fee, so a move to bulk billing is likely to perform better in practice than the curve suggests. It does not model the 180-day backdating of BBPIP registration, the quarterly timing of loading payments, or the eligibility questions the assumptions list sets out.

It is a decision model, not a liability determination and not tax advice. Confirm your position with your accountant or a registered tax agent before you change your billing policy.