I just realized I forgot to attach Schedule B to my 2015 Form 1040 that I filed in April. What should I do now?

Foreign tax credit

A credit for income taxes paid to a foreign country or U.S. possession. 401(k) plan. A deferred pay plan, authorized by Section 401(k) of the Internal Revenue Code, under which a percentage of an employee’s salary is withheld and placed in a savings account or the company’s profit-sharing plan. Income accumulates on the deferred amount until withdrawn by the employee at age 59?