Thousands of people with health insurance are paying twice when they use public hospitals, even if they end up on a trolley.
Patients with health insurance are being targeted by public hospitals when they are admitted.
They are being asked to sign a waiver form, which means they give up their right to be treated as a public patient.
Their insurer gets charged up to €800 a night, instead of €80 a night. Insurers are then passing on the charge to members in the form of higher premiums.
This is despite the fact that they are being treated in a public ward, and may have come to the public hospital from a public waiting list.
It even happens when people sign the form even though they may be stuck on a trolley, never mind getting a private room.
The Government has admitted that charging people with health cover for treatment in a public ward has raised €200m a year, a multiple of what it was initially believed the charges would generate.
However, a new survey has found that the vast majority do not know that they are being hit twice.
The survey, commissioned by Insurance Ireland, found that 65pc of people are unaware that those with health cover are now being pushed into paying twice for the use of a public hospital - through their taxes and through their health cover. The change was introduced in recent years as a way for hospitals to raise additional money.
The survey, carried out on 1,000 adults, found 81pc of those with cover who are admitted to a public hospital are now being asked to sign forms waiving their right to be treated as public patients.
The research, carried out by Ipsos/MRBI, found that 78pc of adults feel it is unacceptable to be charged twice for treatment in a public hospital.
The fact that those with health insurance who use a public hospital are having the cost charged to their insurer is pushing up the cost of premiums, experts say.
In the last two weeks, Laya Healthcare blamed the hospital charges for its move to hike the cost of 124 policies by 6pc from next month.
Insurance Ireland chief executive Kevin Thompson said: "We believe that asking private health insurance customers to pay twice for a service they are already entitled to, once through taxation and again via their health insurance, is not fair or equitable and amounts to double taxation."
He said the measure had added €200m in additional claims costs to the system, and needed to be reviewed.
Health insurance broker Dermot Goode said the double charging would continue to push up the cost of premiums.
"Even though this charge is permitted under recent legislation, one has to question the practice whereby any service provider can charge consumers for a service they have no intention of providing or no capacity to provide, ie private services in this regard," he said.
Mr Goode said that under the old regime, private charges could apply only if the member received private treatment, such as a private room or a transfer to the care of a consultant of their choice.
Now, consumers are being charged even though they remain in a public ward.
"We wouldn't tolerate this in any other industry," Mr Goode, of TotalHealthCover.ie, said.
A spokeswoman for the Department of Health said beds in public hospitals were no longer designated as public or private. Having private health insurance was optional and had no effect on people's statutory entitlements or obligations, she added.