Expats and visitors to Britain who are not entitled to free health care will have to pay upfront for their treatment.
New rules aimed at stopping medical tourism will have to show identification proving they can have free care from hospitals, doctors, community health councils and NHS funded charities.
If they cannot prove their right to free healthcare, unless the case is an emergency, staff will demand a fee of 150% of the cost of the service.
Doctors claim the measure that is now in force across the UK could mean seriously ill people do not seek treatment and that the number of untreated infectious diseases could rise.
NHS hospitals have charged for treatment for some time, but the scheme involved sending out bills after treatment.
Skipping the country
Many remained unpaid as the patients refused to hand over the cash or simply skipped the country.
The new legislation passed through Parliament without any debate in the Commons or Lords.
The Department of Health explained the charges were for planned treatments and that no one would be denied emergency care, although some services would be billed once the patient left hospital.
Health minister James O’Shaughnessy said: “The NHS is a cherished national institution that is paid for by British taxpayers.
“We have no problem with overseas visitors using our NHS as long as they make a fair financial contribution, just as the British taxpayer does.
Medical staff confused over the rules
“The new regulations simply require NHS bodies to make inquiries about, and then charge, those who aren’t entitled to free NHS care. All the money raised goes back into funding and improving care for NHS patients.”
Medical professionals are less confident about the scheme.
A survey in Manchester and the North West revealed NHS staff were confused over who had to pay for treatment, while 80% could not work out if asylum seekers, refugees or failed asylum seekers had to pay.
Almost a third of medical staff believed failed asylum seekers were ineligible for emergency health care, which is not correct under the new rules.
Other research claims patients have been wrongly charged for treatment or charged for procedures that are outside the payment rules.