Most Hunter GP clinics will be affected by a state payroll tax ruling on medical centre contracts, raising concerns about their financial viability.
Revenue NSW - the state tax office - published a ruling on August 11 that confirmed many independent GPs working in medical centres would be subject to payroll tax.
"It will affect most GP practices, as most work with GPs in a contracted arrangement," said Dr Fiona Van Leeuwen, chair of the Hunter General Practitioners Association.
Dr Van Leeuwen said if GP practice owners were "pushed to increase patient fees to cover a state payroll tax on contracted GPs", more people would be priced out of seeing a doctor.
"People will get sicker and present later for urgent care for avoidable escalations of simple health problems," she said.
"Our health system will pay three to five times as much when those sicker people present later to seek care in hospitals and elsewhere, rather than early and routinely with their local GP."
She said the tax would force practices to close.
"This will leave even more people with no regular daytime GP to cost-effectively triage and manage their health needs."
The Royal Australian College of GPs [RACGP] has written to NSW Premier Chris Minns calling for independently contracted GPs to be exempt from payroll tax.
It also wants the government to confirm that general practices were "not being targeted for retrospective tax collection".
GP practices pay payroll tax on their employees, including receptionists, GPs in training and nurses.
"But it hasn't applied to GPs because most doctors are not employees - they lease rooms from a practice owner and work under independent agreements," RACGP president Dr Nicole Higgins said.
"The state's move to boost payroll tax revenues by targeting practices will undermine the federal government's investment and reforms to improve access to GP care - such as tripling bulk-billing incentives."
A NSW government statement said the ruling was "not a change in position" and Revenue NSW was "not engaged in a targeted audit campaign directed at general practices".
But the RACGP said several practices in regional NSW had "received retrospective payroll tax notices, including one for $450,000, with just 21 days to pay".