15 Dec 2013 8:01 PM:
Reading carefully Article 22:-
Article 22
ELIMINATION OF DOUBLE TAXATION
1. In Spain, double taxation shall be avoided following either the provisions of its internal legislation or the following provisions in accordance with the internal legislation of Spain:
a)
(i) (ii)
Where a resident of Spain derives income or owns elements of capital which, in accordance with the provisions of this Convention, may be taxed in the United Kingdom, Spain shall allow:
as a deduction from the tax on the income of that resident, an amount equal to the income tax paid in the United Kingdom;
It seems to me that you have to tell Spain how much tax you have already paid in UK so that a) (i) (ii) can be applied.
Thread:
Income tax on UK State pensions in Spain
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