An additional tax on working graduates would be unfair, the Democratic Alliance Youth said on Thursday.
"It would mean an extra payment on top of their income tax, at a time when many are struggling to make ends meet," federal DA Youth leader Makashule Gana said in a statement.
"Under these circumstances, a graduate tax could actively discourage students from entering tertiary level education."
Gana said many students were still battling to pay off student loans. Student loan debt in 2009 was around R3 billion and had risen since then.
The African National Congress took a resolution at its elective conference in Mangaung last year to introduce a tax on graduates.
Conference delegates participating in the education and health commission resolved that consideration "must be given to a graduate tax for all graduates from higher education institutions".
There were no other details given.
Gana said there was currently no guarantee that a graduate would get work.
"Instead of a tax, we need a youth wage subsidy to help young people find work when they finish school.
"We must not crush the spirit of young people with taxes," he said.