There are conflicting stories on how much lump sum/one off amount can you take from your pension if resident in Spain and what the tax will be. Indeed, many people with UK pensions believe it is better to take their UK pension lump sum in the UK before (grey line here if they have already moved!) they move to Spain permanently, as they will pay less tax. Firstly, even if you have a UK pension but are resident in Spain, this has to be declared in Spain. Secondly, if you finished contributing before 2007 you actually can receive MORE tax relief in Spain than in the UK (dependent upon the pension you have and how you take it).
To clarify, in the UK you can currently take a 25% tax free amount from all your private pensions and anymore would then be taxable.
If resident in Spain, you have the right to take up to 100% of your personal pensions in one go (100% in capital), to receive part in capital and part through regular payments or to receive the whole amount through regular payments. If you receive an amount in capital (a whole or a part) then you can apply for a tax reduction of 40% of the amount received for any contributions you made prior to 2007. This option can only be applied once, so, if you have more than one pension plan, you have to receive all of them in the same tax year if you want to apply this reduction.
If you take the amount as a regular payment you will have to pay income tax as if you have received any other general taxable income (a salary for example). In both of these cases, the amount that is taxed (with or without the 40%) is subject to the general income tax rate.