Lawmakers want to expand the country’s tax base and rein in the national debt, but a plan to extract taxes from companies that operate in free trade zones has some investors worried.

“A regulation like this one throws a curve,” said William Ernest, general manager of Chicago-based cable and fiber optics maker Panduit, who said he is waiting for the tax debate to end before deciding whether to locate a $2 million software development center in Costa Rica or Romania.

The tax plans being discussed would require new free-trade zone companies to pay up to $100,000 in municipal taxes and would include a 15 percent tax on dividends from 2015.

Only businesses that arrive in or after 2015 would be affected, said Gustavo Arias, a lawmaker working on the bill.

“In reality it’s very little for these companies to pay,” said Arias, of the left-of-center opposition Citizen Action Party.

Opponents of the plan said nerves are rattled across the free trade zones, where computer chip giant Intel, computer maker Hewlett Packard and a host of multinational medical device makers and food and beverage companies have plants.

Their combined economic input in Costa Rica, in salaries and local operations, equaled 8 percent of gross domestic product last year, according to a new study by the Costa Rica trade promotion agency.

President Laura Chinchilla’s administration ran a deficit equal to 5.3 percent of GDP last year, the highest in Latin America, and has made a hard push for Congress to approve her tax reform package, which aims to raise around 2 percent of GDP in new state revenue.

Lawmakers expect tax reform to pass by December.