The account carries interest of 4%.

该存款有4%的利息。

The interest is added to your account every year.

每年的利息都加到你的存款中。

The interest rate for the savings account is 4%.

储蓄存款的利率是4%。

It varies from time to time. At present it is 6%.

（年息）每个时期都不同，现在是六厘。

Useful Words and Phrases

interest rate 利率

simple interest 单利

compound interest 复利

legal interest 法定利息

prime rate 优待利率

payable interest 应付利息

lending rate 贷款利率

usury 高利贷

the subsidy rate for value-preserved savings 保值储蓄补贴率