Apple CFO Luca Maestri said a U.S. border tax would harm the world's largest economy by raising costs for consumers and making it harder for companies to compete overseas.

A border tax also would increase the value of the U.S. dollar, which is already too strong, and reduce the competitiveness of the country's economy, Maestri said Tuesday at a technology conference in San Francisco sponsored by Goldman Sachs Group Inc.

President Donald Trump and the Republican-controlled Congress want to rewrite U.S. taxes in ways that may help and hurt Apple, the world's most valuable public company. One proposal would cut the corporate tax rate to 20% and tax U.S. companies on their domestic income and imports, while exempting their exports and offshore income. Companies that import a lot, such as retailers, oppose the idea, while exporters have expressed support.