JAKARTA (REUTERS) - Indonesian President Joko Widodo's second tax amnesty programme has unearthed previously unreported assets worth nearly US$600 million (S$810 million) in its first month.

Mr Widodo launched the current amnesty programme on Jan 1 and it will run throughout the first half of 2022. No target has been announced for the value of assets the government hopes will be declared.

The government has described Mr Widodo's first amnesty held for nine months from 2016 to 2017, as one of the world's most successful because it uncovered more than US$300 billion worth of assets previously hidden from tax authorities.

That earned the administration over US$9 billion in revenue from penalties.

Official data showed 9,276 taxpayers joined the programme in January, declaring 8.47 trillion rupiah (S$795 million) worth of assets.

Under the current programme, the authorities count the declared assets as additional income and charge a range of income tax rates based on certain conditions.

Revenue collected from the programme last month reached 903 billion rupiah.

Finance Minister Sri Mulyani Indrawati said the authorities will promote the programme more to make taxpayers aware.

"We will also remind all taxpayers across Indonesia, individuals and companies, to improve compliance," she told a news conference on Wednesday (Feb 2).

Mr Bawono Kristiaji, a partner at local tax firm Danny Darussalam Tax Centre, said the amnesty has been attractive for taxpayers, but also suggested the government partner with other stakeholders to increase awareness.

"Other than that, technical regulation is needed regarding investment for assets that are declared and repatriated, to provide some certainties for taxpayers," he said.

The Organisation for Economic Co-operation and Development has previously advised Indonesia not to repeat tax amnesty programmes to avoid future evasion.