Article 27 provides for a mutual agreement procedure allowing a person who considers that the tax is not in conformity with the Treaty to present his case to the competent authority of the State in which he resides. (52) If the natural person considers that the tax is imposed in breach of the article on non-discrimination, he may present his case to the State of which he is a national. There is a three-year statute of limitations for complaints. In addition, a person shall not waive other remedies available to him or her under national law by exercising his or her rights under the Convention. The competent authorities shall endeavour to resolve any difficulties by mutual agreement. However, paragraph 2 provides that the taxable person`s objection must be `justified` so that the competent authorities can endeavour to resolve the case. (53) Paragraph 3 provides for a number of derogations from the extended reservation of rights referred to in paragraph 2.