JSA has entered into an exclusive association with Singh, who has been an Indian Revenue Service officer since 1971. He is also a qualified advocate.

Singh told Legally India: "I am working exclusively with [JSA] advising them on legal matters pertaining to indirect taxes."

He added that there was flexibility in his current consultancy arrangement although the option of joining the firm as a member in future was not closed.

JSA founding partner Jyoti Sagar said in a statement: "A senior and accomplished person of the calibre of Mr Singh is a valuable addition to the advisory team at JSA and our attorneys and clients will benefit from the wealth of his experience."

Sagar was not immediately available for comment at the time of going to press. [We will update the story once we receive an official comment. -Ed].

According to JSA, Singh retired in December 2009 as chairman of the Customs and Central Excise Settlement Commission after working with the revenue service for 39 years.

In December 2009 JSA hired an AZB lawyer as a partner to create a direct tax practice at the firm.

JSA's indirect tax team is headed by partner Ashok Dhingra, who had joined from Khaitan & Co in March 2009.

Indirect tax has also been a boom hiring area for law firms since late last year, when AZB & Partners hired an indirect tax partner and Vaish Associates hired two indirect tax practitioners.

Singh said that he, like other lawyers, was expecting that clients would require specialist advisory capacity with the onset of the new goods and services tax (GST).