TAIPEI, May 28 (Reuters) - The U.S. has no timetable for levying Section 232 tariffs on semiconductors but preferential terms have already been agreed under a January trade deal, Taiwan Vice Premier Cheng Li-chiun said on Thursday.

• The U.S. is removing or cutting some tariffs to 15% on Taiwanese imports as part of a bilateral trade deal reached in January, covering goods including auto and aircraft parts, wood and steel, according to a notice on the Federal Register. The tariff move is, in effect, retroactive from May 1 and will be officially published on Thursday U.S. time, according to the notice.

• Under the terms of the January agreement, Taiwan secured preferential treatment in advance under any future measures on semiconductors under Section 232, a U.S. national security investigation into imports of key products like chips and pharmaceuticals.

• Speaking in Taipei, Cheng said the U.S. has repeatedly indicated it might impose Section 232-related tariffs on semiconductors, but Taiwan secured most-favoured-nation treatment for chips with the January deal.

• That means that no matter when the U.S. proposes Section 232 semiconductor tariffs, it must grant corresponding preferential treatment to Taiwanese businesses investing in the U.S., she added.

• These pre-secured preferential treatments will remain unchanged and the U.S. has no concrete timetable for Section 232 semiconductor tariffs, Cheng said.

• Taiwan is a major semiconductor producer and home to TSMC 2330.TW, the world's largest contract chipmaker. TSMC is investing $165 billion to build factories in the U.S. state of Arizona.