Teachers from the Educational Institute of Scotland (EIS) union will discuss the issue at their annual general meeting in Perth, which begins today.
A motion from the union's Dumfries & Galloway local association calls for the EIS executive to campaign for a change in the law "to remove charitable status from independent schools".
The call comes eight years after private schools were confronted with the prospect of losing their long-held status as charities, which is worth millions of pounds in tax breaks.
At the time, Jane Ryder, chief executive of the Office of the Scottish Charities Regulator (OSCR), warned the independent sector would be judged on how effectively it opened its doors to those who would not normally be able to afford a private school.
Subsequently, institutions such as Hutchesons' Grammar in Glasgow, Merchiston Castle in Edinburgh, St Leonards in St Andrews and Lomond School in Helensburgh were warned they needed to do more to pass the new "public benefit test".
However, in April, private schools launched a bullish defence of their contribution to Scottish society and the wider economy.
A report by the Scottish Council Of Independent Schools (SCIS) said the value of the sector to the wider economy was £446 million a year and more than 11,200 jobs.
An accompanying commentary by John Edward, director of the SCIS, attacked the "old assumptions" about the socio-economic background of private pupils in the wake of tough new charities legislation.
An EIS spokesman said: "The issue of charitable status for selected education establishments is a long-running issue of concern for many teachers and lecturers. There is sure to be a lively debate and discussion on the equality implications of the current funding regulations."
However, Mr Edward highlighted figures from OSCR that show more than 400 poorer pupils in Scotland receive a 100% remission on their school fees, in addition to an expansion in means-tested bursaries.
He said: "No group in Scotland is better able to demonstrate their compliance with the requirements to meet charitable purposes.
"Independent schools are charities because they fulfil purposes for the public benefit ... means-tested financial assistance now far outstrips any taxation rates that follow from charitable status."
Teachers at the EIS conference will debate a range of motions, including a number including threats by school staff to go on strike over the roll-out of Scotland's new curriculum.
The move follows a number of national surveys by the EIS highlighting workload as the key issue of concern for teachers during the implementation of new National exams - which replaced Standard Grade this summer as part of the Curriculum for Excellence.
A motion from the union's Renfrewshire local association calls on the Scottish Government, the Scottish Qualifications Authority and curriculum body Education Scotland to ensure better resources are provided for all National courses. It adds: "Failure to deliver this by August 2014 should be followed by an immediate ballot for industrial action." There are also threats to strike over changes to pensions.