Section 509.120 - Double taxation claims(a)General. Under Article XVII of the convention, where the taxpayer shows proof that the action of the tax authorities of the United States or Switzerland has resulted, or will result, in double taxation contrary to the provisions of the convention, he is entitled to present the facts to the country of which he is a citizen; or, if he is not a citizen of either country, to the country of which he is a resident; or, if the taxpayer is a corporation or other entity, to the country in which it is created or organized. The article provides that, should the taxpayer's claim be deemed worthy of consideration, the competent authority of the country to which the facts are presented shall undertake to come to an agreement with the competent authority of the other country with a view to equitable avoidance of the double taxation in question.(b)Manner of filing claim. Such a claim on behalf of a United States citizen, corporation, or other entity, or on behalf of a resident of the United States who is not a Swiss citizen, shall be filed with the Commissioner. The claim shall be set up in the form of a letter addressed to "The Commissioner of Internal Revenue, Washington, D.C." and shall show fully all facts and laws on the basis of which the claimant alleges that such double taxation has resulted or will result. If the Commissioner determines that there is an appropriate basis for the claim under the convention, he shall take up the matter with the Director of the Federal Tax Administration with a view to arranging an agreement of the character contemplated by Article XVII.