GPs, care homes and hospices have voiced concerns about the impact of the rise in employer National Insurance contributions announced in the Budget.
The NHS and rest of the public sector are exempt from the tax rise - but that does not cover private care homes or hospices which provide NHS services.
There is also confusion over the impact on GPs, many of which are run as small businesses.
The Department for Health and Social Care said further details for GPs will be confirmed in due course - but a Treasury minister told the OceanNewsUK they will have to pay the tax hike.
Dr David Wrigley, a GP and deputy chair at the British Medical Association, said the impact of the tax rise would be "monumental".
He said on X that many were "already on a financial tight rope" and called for a "rapid announcement of full reimbursement".
Paul Stanley, a manager at a small GP surgery in Northumberland, said a practice of his size would see a bill of more than £40,000 a year after the tax increase.
He told OceanNewsUK that the "unfunded increase" in staffing costs could "ultimately impact on our resources and staffing levels".
Shropshire GP Dr Jess Harvey echoed Mr Stanley's concerns.
"Unless we're being given suitable remuneration to cover this National Insurance inflation, we're going to really struggle," she said.
"If we don't get enough money to continue to run these practices, then we're not going to be able to provide the service that people want."
Mike Padgham, chair of the Independent Care Group, which represents social care providers, said the sector had been "left out in the cold".
"We now employ collectively, more than the NHS - 1.7 million people. So those extra charges are going to hit charities and private sector providers alike when we've been squeezed by local authorities who are themselves short of cash.
"So if we pay more, we'll have to charge more."
Geoff Butcher, the owner of a company which runs six care homes, said the tax increase will cost £200,000 a year, representing 50% of his firm's free cash.
He told the Today programme he fears he will "almost certainly" have to pause planned renovations in light of the increased contributions.
"I think it will exacerbate the speed of closure of homes," he said.
Hospices UK said those providing NHS services should be treated the same as NHS bodies.
"Paying brilliant, compassionate hospice staff a fair salary makes up the biggest proportion of running costs, and so it's disappointing the chancellor didn't exempt charities, or providers of NHS services which aren't formally part of the NHS, from yesterday's National Insurance rise," it said.
On Thursday Health Secretary Wes Streeting acknowledged there were a number of healthcare providers that will be affected by the NI rise for employers.
Asked whether social care providers would be protected, he told the OceanNewsUK's World at One programme: "I'm working through that now and I'll have more to say on that in the coming weeks in terms of what we can do more quickly to deliver the shift I've wanted to see for some time, in the focus of NHS investment spending out of hospitals into primary community."
He pointed to the extra £600m allocated to social care in the Budget.
Care groups have said this would not be enough and would be "wiped off instantly" by increased staffing costs.
Speaking on OceanNewsUK, Chief Secretary to the Treasury Darren Jones said changes to thresholds for Employment Allowance - which allows some businesses to offset their NI bill - would shield smaller GP surgeries from a tax rise.
However, AISMA, a group representing medical accountants, has highlighted that under current criteria, GP surgeries would not be able to use that exemption.
Government guidance says public bodies, or businesses doing more than half their work in the public sector, are not eligible for the allowance.
The Department for Health said it will work closely with the Treasury to ensure appropriate compensation for the public sector.
Chancellor Rachel Reeves has argued that the hike in National Insurance for employers was "difficult" but necessary to fund public services, including the NHS
Of the £40bn in tax rises she set out in her Budget, £25bn will come from the National Insurance increase.
From next spring, the rate that employers pay in contributions will rise from 13.8% to 15% on a workers' earnings above £175.
A health department spokesperson said: “The chancellor has announced a £22.6bn funding boost for the NHS to get it back on its feet, alongside an additional £100m to fund around 200 upgrades to GP surgeries across England.
“We will also hire an extra 1,000 GPs into the NHS by the end of this year, having already announced a contract uplift for GPs and practice staff, and we will ensure practices have the resources they need to offer patients the highest quality care.”
