James Evans fears that social care providers and GP practices will be hit by national insurance increases being imposed on employers.
The Brecon and Radnorshire MS said at the Senedd this week that the NHS will be exempt from the rises, but social care providers and GP surgeries are not.
Mr Evans said: “They have raised serious concerns that tax rises could impact the delivery of the services they provide in looking after the most vulnerable sick people.
“A lot of practices and social care providers are locked into contracts with health boards and local authorities.”
He asked Finance Secretary Mark Drakeford what assurance he could provide that the Welsh Government will support them through these tax rises to make sure that people in Wales can still access the services they need.
Mr Drakeford said Mr Evans had raised important points that will be discussed by Cabinet members as they deploy the resources available to them.
He said: “I've heard very clearly the points he's made this afternoon.”