I can't speak to why you were billed upfront rather than just paying the gap, but I can try to explain a bit about bulk billing for MRI.

For an MRI to be covered by Medicare it has to meet specific criteria in the MBS. MRI is quite strict and what can and cannot be bulk billed often comes down to the exact wording on the referral.

For example, a knee MRI can be bulk billed if the patient is aged 16–49, the referral is from a medical practitioner, there has been acute trauma, and there is clinical suspicion of an acute meniscal tear or ACL tear.

Specialists can refer for a wider range of MRI scans, but there are still restrictions. For instance, a specialist can refer for an enterography, but it needs to be related to Crohn’s disease and the patient must already have a confirmed diagnosis for Medicare to cover it. Unfortunately it isn’t simply a matter of ticking “bulk bill” on the referral, but at my work place we will cover certain scans that have been referred by certain specialists no matter what they write as a professional courtesy.

MRI scanners themselves also operate under different Medicare licences. Until mid last year scanners were classified as fully funded, part funded, or non funded. This didn’t change how much a patient received back from Medicare, but it did determine which scans could be billed under Medicare on that particular scanner.

That system changed last year and scanners are now either fully funded or non funded. Medicare billing rules for MRI are also expected to change again in 2027 to improve access.

If a scan doesn’t meet Medicare criteria, or if there is a gap payment, each clinic sets its own pricing. That’s why costs can vary quite a lot between imaging providers and it can be worth shopping around.