Foreign Pension- treatment with reciprocal treaty
What is the number of the form that taxpayers with pension from a foreign country must file . The country has a reciprocal treaty with USA and the pension is taxed in the foreign country.
What is the number of the form that taxpayers with pension from a foreign country must file . The country has a reciprocal treaty with USA and the pension is taxed in the foreign country.

You should be able to find your answer here:
Form 8833 - Treaty Based Return Position Disclosure.