Article 14.3 of the original Agreement stipulates that when a person qualifies for U.K. invalidity benefits through application of the Agreement, the amount of the benefit must be prorated based on the ratio of the person’s periods of U.K. coverage to the combined duration of U.K. and U.S. coverage.  This pro rata computation is similar to the method provided in Article 11.2 of the Agreement for computation of U.K. old-age and retirement benefits that are based on totalization.

Articles 9 and 11 of the original Agreement include several additional rules for calculating the amount of U.K. pro rata old-age and retirement pensions and, in accordance with Article 14.3(a), these rules also apply for the calculation of U.K. invalidity benefits.  The Supplementary Agreement, however, revised Article 14.3(a) to remove references to several of these provisions—Articles 9.3 and 9.4 and Article 11.5—with the result that the omitted provisions no longer apply in computing the amount of U.K. invalidity benefits.

Articles 9.3 and 9.4 provide for converting U.S. quarters of coverage into equivalent periods under the systems of Jersey and Guernsey.  Under the Supplementary Agreement, however, the amount of Jersey and Guernsey invalidity benefits based on totalized         periods of coverage will no longer take into account the duration of a person’s U.S. coverage, and it is no longer appropriate, therefore, for Article 14.3(a) to refer to Articles 9.3 and 9.4.

Article 11.5 of the original Agreement stipulates that in determining the amount of U.K. pro rata old-age or retirement pensions, under certain conditions periods of U.S. coverage may be assigned to a U.K. tax year other than the one in which it actually falls.  The United Kingdom no longer considers this provision relevant for the calculation of U.K invalidity benefits; the Supplementary Agreement, therefore, amended Article 14.3(a) to exclude reference to this provision as well.