U.S. President-elect Donald Trump pledged last month to eliminate "the double taxation of overseas Americans.”

Never mind the clumsy wording — taxes on U.S. citizens working abroad aren’t excessive so much as excessively complicated — this is one campaign promise that may actually be fulfilled, given the Republican control of both houses of Congress. That would be a good thing not only for those Americans but also for America.

There is in fact a long-standing debate over getting rid of what is commonly called "citizenship-based taxation” and replacing it with "residence-based taxation,” which is standard practice around the world. America’s system is different. If you are a U.S. citizen but do not live, work or earn income in the U.S., you are still liable for U.S. taxes. There are as many as 9 million Americans living abroad, a substantial population.