The National Tax Service is planning to strengthen its legal team by adding a group of attorneys to assist in corporate litigation, the nation’s tax office said Monday.

The overhaul comes after the tax agency lost some major high-profile lawsuits, leading it to incur losses of up to 717.9 billion won ($667.3 million) last year.

The renewed legal team will focus on fighting legal battles against major law firms, while its original tax collection duties will be outsourced to another division, the tax agency said.

“We’re reviewing plans to hire an outside expert as the head of the strengthened team,” a high-ranking NTS official told the local media.

The NTS said it will start the reshuffling in January at the Seoul Regional Tax Office, which has lost the highest number of lawsuits among the agency’s six regional offices.

The Seoul office accounted for 86 percent, or 617.9 billion won, of the losses incurred by the NTS after losing lawsuits, according to a report by ruling Saenuri Party lawmaker Park Myung-jae.

The agency has faced a barrage of criticism for losing against larger law firms such as Bae, Kim & Lee LLC and Kim & Chang as it struggled amid mounting pressure from the Park Geun-hye government to recover delinquent taxes and in general increase tax revenues to finance its welfare policies.

NTS commissioner Lim Hwan-soo has repeatedly talked of the need for agency reforms to better handle litigations, saying that winning lawsuits were another critical part of the agency’s tax investigation duties.

By Suk Gee-hyun (monicasuk@heraldcorp.com)