Changing the way patients pay the cost of their treatment is being mooted as a way of reducing health system costs.
A Treasury report warns government spending on health could rise from around 7% of GDP now to over 11% of GDP by 2060.
It suggests there is scope to see if more, or different co-payment arrangements could reduce demand for health care.
Co-payments systems already apply for prescription charges and GP visits.
The report warns if co-payments were too high they could deter people from getting care.
It also says the approach is regressive but could be mitigated by targeting people on higher incomes.