The NSW Government must immediately investigate the failure of 7-Eleven's 231 stores in the state to pay payroll tax, the state Opposition has said.

Labor's Daniel Mookhey said Freedom of Information documents revealed 7-Eleven and its franchisees had paid no payroll tax in NSW for at least the past three years.

Mr Mookhey said the money could have gone towards nurses and paramedics.

"The victim's of the NSW Government inaction are the honest businesses that do pay their taxes," he said.

The revelation comes in the wake of a scandal over 7-Eleven employees being underpaid by as much half the minimum wage.

The Labor Party asked why the Baird Government was not seeking the money it is owed.

In Victoria, the Office of State Revenue is investigating the company's payroll tax compliance.

Mr Mookhey said the NSW Government was relying on that investigation to collect money owed to it.

A spokesman for the NSW Government said the issue was more of an operational matter than a political one.

The NSW Office of State Revenue said its Victorian counterpart would lead the investigation into the alleged payroll tax rort by 7-Eleven.

But spokesman Steve Brady said it was unclear if anything was owed to government coffers.

"All other states are co-operating with Victoria," he said.

"Victoria is taking the lead on this investigation. We are working very closely with them, but at this stage there are no findings for liability."

The NSW Government said it was not aware of any payroll tax liability for the 213 7-Eleven stores across the state.