The South African Revenue Sevice (Sars) investigation into President Jacob Zuma’s tax liability in relation to his Nkandla homestead was ongoing and “painstakingly slow”, MPs were told on Tuesday.

While briefing Parliament’s standing committee on public accounts (Scopa), members of the anti-corruption task team (ACTT), which included Sars commissioner Tom Moyane, were asked about the progress of various cases before it.

Moyane referred questions on Zuma’s tax on fringe benefits related to Nkandla to Neo Tsholanku, acting chief officer: legal at Sars.

“Tax matters by their very nature are matters that pertain to the taxpayer and the Sars, that then creates problem for us to give details …,” Tsholanku said, indicating that because engagements between the revenue service and taxpayers were confidential, he could not provide details.

Tsholanku said because the matter involves complex processes such as audits, it would not be resolved overnight.

“By their very nature, they are complicated. It’s difficult to say when you conduct an audit what you will find. Our auditors are working as fast as they can …,” he said.

African National Congress MP Mnyami Booi was not happy with this answer, telling Sars not to “transgress and undermine us”.

“You are turning us into a laughing stock.”

Last year, National Treasury determined Zuma had to pay back R7.8-million for non-security upgrades to his Nkandla homestead in KwaZulu-Natal after the Constitution Court found he was liable to pay back a portion of the R250-million spent on non-security improvements.

In addition, Zuma would have to pay tax on fringe benefits he accrued as result of the upgrades.