[X1Article 21 U.K. Cash benefits
1. An insured person and members of his/her family residing or staying in a Member State other than the competent Member State shall be entitled to cash benefits provided by the competent institution in accordance with the legislation it applies. By agreement between the competent institution and the institution of the place of residence or stay, such benefits may, however, be provided by the institution of the place of residence or stay at the expense of the competent institution in accordance with the legislation of the competent Member State.
2. The competent institution of a Member State whose legislation stipulates that the calculation of cash benefits shall be based on average income or on an average contribution basis shall determine such average income or average contribution basis exclusively by reference to the incomes confirmed as having been paid, or contribution bases applied, during the periods completed under the said legislation.
3. The competent institution of a Member State whose legislation provides that the calculation of cash benefits shall be based on standard income shall take into account exclusively the standard income or, where appropriate, the average of standard incomes for the periods completed under the said legislation.
4. Paragraphs 2 and 3 shall apply mutatis mutandis to cases where the legislation applied by the competent institution lays down a specific reference period which corresponds in the case in question either wholly or partly to the periods which the person concerned has completed under the legislation of one or more other Member States.]