UPDATE 3-Mexican tax chief Raquel Buenrostro named as next economy minister

(Updates with line on Buenrostro's replacement in the tax office)

MEXICO CITY, Oct 7 (Reuters) - Mexican President Andres Manuel Lopez Obrador named Raquel Buenrostro as economy minister Friday, putting the head of the country's tax authority, who made her name cracking down on big business for unpaid taxes, in place to lead efforts to fix a major trade dispute with the United States.

"She's done a great job (as tax authority chief)," Lopez Obrador said at a regular news conference, touting Buenrostro's experience in the public sector and master's degree in economics.

Former Economy Minister Tatiana Clouthier stepped down Thursday, leaving her ministry without a key negotiator amid trade disputes with the United States and Canada. She did not say why she was leaving the post.

Buenrostro became head of the country's tax authority, SAT, in early 2020. She is set to be replaced in her former role by the finance ministry's tax prosecutor Arturo Medina, sources told Reuters Friday.

As tax chief, Buenrostro spearheaded efforts to crack down on tax evaders. Lopez Obrador said last month dozens of companies owed a total of around 100 billion pesos ($4.99 billion) in taxes.

Walmart's Mexican unit Walmex and Coca-Cola bottler FEMSA paid out hundreds of millions of dollars in taxes in 2020 after reaching agreements with authorities.

"(Buenrostro) was able to reap the benefits of her predecessors," said Miguel Angel Estrella, a former SAT official who now runs an international consulting firm.

"These auditory processes... take a year and eight months (at least). When it's a judicial case, that's three to five years," Estrella said.

Now, Buenrostro will be tapped to head discussions with the United States and Canada under the USMCA regional trade pact, including an ongoing dispute over energy.

The dispute, filed by the U.S. and joined by Canada, alleges the Mexican government is slow to grant energy permits and prioritizes state firms, according to industry sources.

"If Mexico had continued giving (energy) concessions... it would have been really beneficial for Mexico," said Estrella, who said he had worked with a firm that opted to move operations to Panama over Mexico due to energy concerns.

Prior to joining the SAT, Buenrostro also worked at Mexico's finance ministry's budgetary unit and for Petroleos Mexicanos, the state-run oil company.

"It's not clear to me if her profile is one of a negotiator," Estrella said. ($1 = 20.0312 Mexican pesos) (Reporting by Kylie Madry; editing by Cassandra Garrison, Kirsten Donovan and Chizu Nomiyama)