Health chiefs in Blackpool have warned a 'tax trap' affecting senior doctors around the country could impact patient care on the Fylde coast.
A combination of tax and pensions rules means medics on top salaries around the country have been faced with high tax bills if they cross an earnings threshold.
This has led to some cutting back on overtime and weekend work.
Chief executive of the Blackpool Teaching Hospitals NHS Foundation Trust Kevin McGee told a meeting of the board: "It is a national problem that is replicated within the Fylde coast and Blackpool.
"It is a particular problem going into winter because the NHS flexes capacity upwards to ask staff to do more sessions.
"However it can be a financial impediment to do more work so we are seeing both locally and nationally some sessions being dropped and that will potentially cause problems coming into winter.
"We are looking at how we can cope with this. We are looking to flex other disciplines and professions to see how we can increase sessions, but it is a problem."
Health chiefs are also continuing to prepare for a possible exit from the European Union during the winter months in line with the new date for Brexit of January 31.
Berenice Groves, one of two directors of operations, said the new date came at an already challenging time for the health service when it was already coping with additional winter pressures.
Mr McGee added: "There is a nervousness going into winter, not just around Brexit but around pensions.
"The real focus will be to do the right thing around patient safety which is what we will always do."