If a person resides more than 182 days in any calendar year in Spain, then that person will be deemed a resident in Spain for tax purposes. Persons spending less than this period, will be deemed non-resident for tax purposes. That said, it is impossible to establish exactly ones tax situation, without detailed knowledge of the personal circumstances.
The authority responsible for the collection of taxes is the “Agencia Estatal Tributaria” (AEAT-Hacienda), which is organised on a provincial basis. In each province there is a main office of Hacienda, and in many provinces there may be one or more sub-provincial offices.
There is an important difference between the way in which the Spanish and the British pay their taxes, because in Spain it is a personal responsibility and obligation to complete a tax return each year, by making a self assessment of the amount to pay, and submitting the form to the Hacienda together with the amount due.