Beiderbeck Dunleath

This question is linked to my own of a few days ago, to which I cannot find any answer. I do need the moderator to answer the questions accurately and in good time for submitting the Spanish tax return for 2023, due next month, June 2024. Under the DTT of 2013, there is no requirement to submit a tax return in the UK regarding a UK Government Service Pension. The P60 does seem to be needed for entry at box 470 on the tax (Spanish) return, for the purpose of assessing the%rate of tax for other world wide income taxable in Spain. In my case adding this detail to the UK state pension using, or misusing the taxed UK government service pension detail . I cannot find any answer, in the DTT pages or the Tributaria web site. It looks as though the negotiators did not pay attention to the right of the Spanish state to continue to do this. So, I think I am being subject to a variant of double taxation, and wonder if this is fair, or can be appealed. Moderator, please answer this query as well as the one from Daniel.

My first post, linked to the previous post. Tax resident in Spain since 2004, my bad experience with the DTT 2013 was eventually resolved by HMRC intervention with Hacienda, following which around 3000euros has so far been refunded, as I had been taxed on the LGPS . However, it seems there is still a form of double taxation (as I see it) via box 470 of the tax return. The info from the P60 is inserted for addition to any income taxable in Spain, for the purpose of calculating the %tax rate on income only taxable in Spain. (In my case the DWP pension) this total tips my rate of tax from 19% to 24% on the DWP pension. My understanding is that Spain can do this under their own rules. It does seem a bit harsh to increase that tax rate on just a UK state pension by this means, using income covered by the DTT 2013.