Shui Poh Sing, 60, who owns a business popularly known as Ah Seng Durian with his brother, was yesterday sentenced to three weeks' jail and fined $5,000 for evading taxes. He was also ordered to pay a penalty of $77,077.91.

Shui and his brother Poh Chung, 57, had earlier pleaded guilty to not paying taxes, including failing to register for goods and services tax (GST) when their revenue exceeded $1 million.

The younger brother was fined $10,000 and ordered to pay a penalty of $46,303.14 last Friday.

The prosecution had sought a jail sentence for the older Shui, who is the managing partner of the firm and in charge of its accounts and record keeping.

The duo had admitted to underdeclaring their income by about $708,000 for six years. This resulted in $161,604.62 in taxes undercharged.

The court heard last week that they had inherited Shanghai Moh Lee Seng minimart from their father, who died in 1999.

It ceased operating on Feb 20, 2012, and they moved the business operations to Seng Chung Trading, also known as Ah Seng Durian, which they had set up.

Senior tax prosecutor Patrick Nai of the Inland Revenue Authority of Singapore told the court the undeclared income Seng Chung Trading earned from durian sales was used to finance mortgage payments for the brothers' respective properties in Malaysia.

He added that Shanghai Moh Lee Seng's turnover crossed the $1 million threshold for GST registration on Dec 31, 2006.

Under the GST Act, the older Shui was required to notify the Comptroller of GST and register the business for GST by Jan 31 the following year but failed to do so.

Defence lawyer Vinit Chhabra told District Judge Adam Nakhoda that there was a mix-up which could be attributed to the brothers using one single bank account for both their private and business matters.

Income went into the account and payments went out, without a fixed method of keeping track.

Mr Chhabra said the older Shui handled the accounting work of the business, despite having no training in accountancy, and this could have led to some lapses.

The older brother took up the task when their accountant retired after their father died, the lawyer told the court.

But after investigations into their tax offences started in 2014, the two brothers engaged a professional accountant the following year to ensure their books are in order, said Mr Chhabra.