Only 30% of motorists paid their e-toll invoices over the past two years, according to a report by Fin24.
Responding to a question asked by the DA, the Department of Transport said 30% of e-toll invoices issued from April 2015 to March 2017 have been paid.
1.8 billion invoices were issued during this period, 1.3 billion of which remain unpaid.
According to Sanral, the compliance rate of e-toll users is calculated using a rand value, as invoices can vary depending on numerous factors.
Sanral said the compliance rate of e-toll users for February 2017 was 29%.
The DA also requested the total value of outstanding e-toll debts, but Sanral said it could not provide this figure as its year-end processes and audits need to be completed.
The department said registered and non-registered e-toll users would be taken to court for not paying invoices, depending on the merit of the case.