4. Where a person other than a natural person or a company resides in both States Parties pursuant to paragraph 1 above, the competent authorities of the States Parties shall decide by mutual agreement on the matter and determine the nature and mode of action of the Convention in respect of that person. 6. Periodic payments for the maintenance of a minor child, made on the basis of a written separation agreement or divorce order, separate maintenance or maintenance and which are paid by a resident of a Contracting State to a resident of the other Contracting State, may be taxed only in the first-mentioned State. Capital gains are the difference between consideration and cost, which are adjusted by the inflation index, but in some cases no indexation is available.