Interest Equalization Tax

The goal of the interest equalization tax was to discourage Americans from buying foreign securities, in an effort to help the country's balance of payments.

The law was first passed in 1963 and lasted until 1974. The IES carried a 15% tax on foreign stocks. It had a sliding tax scale for bonds, based on maturity.

At the time, politicians feared that too much capital was leaving the U.S., with Americans buying things like foreign stocks or bonds. The tax was a kind of tariff for financial instruments. It was meant to make buying the foreign securities more expensive in order to discourage Americans from buying them. Presumably, they'd then stick to Treasuries and apple pie futures.