UPDATE 1-Mexico's finmin has no precise date for tax plan

(Recasts with comments on tax reforms)

By Ros Krasny

CHICAGO, May 31 (Reuters) - Mexican Finance Minister Agustin Carstens said on Thursday there is no precise date for presenting the government's keenly awaited tax reform proposals to Congress.

"There's a lot of dialogue," Carstens told reporters after a speech in Chicago. "So far it has been a respectful, constructive dialogue."

The government "still needs to work very closely with Congress" on the tax reform plan, Carstens said.

He declined to comment on whether financial markets are overly optimistic on the timing or the content of the proposals, which Mexican President Felipe Calderon said this week would be unveiled "soon."

Mexico's peso firmed to its strongest close in seven months on Thursday as investors took Calderon's words at face value.

Mexico's tax take is one of the smallest in Latin America relative to the size of its economy, and economists say boosting fiscal revenues could boost economic growth and possibly result in an upgrade to Mexico's credit rating.

"Our approach will be a gradual one, but a solid one" that features "a simple system and the lowest possible rate," Carstens said of the tax plan.

"We want to ... establish a solid taxation regime that for the next 10 to 15 years will allow us to gradually increase our tax revenue."

Earlier, in comments to the Chicago Council on Global Affairs, Carstens said he was worried that a rapid adjustment in the huge U.S. current account deficit could hurt Mexico's economy by slashing demand for imports.

"We're worried that this imbalance, this very large current account deficit that the United States has, will at some point lead to ... a drop in U.S. consumption that will hurt Mexico," he said.

The United States is Mexico's main trade partner.

Carstens also said that Mexico now has more normal business cycles compared with its crisis-prone economy of the past, and an inflation rate more in line with developed economies.

"We have a very solid macroeconomic framework," he said.

Addressing the hot topic of immigration, Carstens predicted that the one-way street of Mexicans moving north will become more balanced in the next few decades as more U.S. and Canadian retirees seek out the lower cost of living in Mexico.

It would make a "huge difference" if U.S. retirees could use Medicare to pay medical bills in Mexico, he said, adding that a decision on that topic was in the hands of U.S. lawmakers.