When you turn up in an A&E ward in a public hospital these days you join a queue, often a long one.
At some stage, before you get treated, you will be asked if you have a medical card, if you pay PRSI and whether you have health insurance.
Even though you are about to be treated as a public patient, in a public ward, you will be asked sign a form waiving your right to be treated as a public patient if you acknowledge that you have health cover.
One woman who went through this said she had been referred to Beaumont Hospital in Dublin for a procedure as a public patient.
As the treatment was not urgent, she had decided to wait and be treated publicly, as is her right as a taxpayer.
"I was asked to sign various forms. I pointed out to the young man I was not a private patient, and I had waited 14 months. 'This is the procedure,' he assured me," she said.
"A week later the Vhi sent me a form to sign. Upon inquiry, they tell me they were billed €1,400 for this procedure." She said the practice was underhand.
Cash-strapped hospitals are charging insurers for private services they are not providing as a way of generating extra revenue.
What they are actually doing is milking private patients, despite treating them as public patients.
Patients are being advised by the hospitals that the charge is fully covered by their insurers, and there will be no cost to them at all.
But this is completely misleading, as they are paying for this indirectly through higher premiums.
They are being charged double - through their taxes, and again on their insurance cover.
When health insurance customers sign the form in public hospitals their health insurer is charged €813 a day. Those treated as public patients pay €80.
It is estimated this charge alone could be adding as much as 5pc a year to the cost of private health cover.
Up to 2014, hospitals could only charge for so-called designated beds. And just 20pc of beds in public hospitals were set aside for those with health cover.
But the law was changed. The then health minister James Reilly promised the change would only cost health insurers €30m a year.
It is now costing them, and those of us with health cover, €200m a year, according to Department of Health figures.
When health insurance customers are asked to sign the waiver form, they should ask what additional services they are going to receive.
If they are being treated as a public patient, with no private or semi-private bed and no treatment from a consultant of their choice, then they should not sign it.
It is becoming clear the double charging is nothing more than a sneaky subsidy for a public hospital system where costs are out of control. And it is a subsidy that puts those who pay for everything on the hook again.