Declaring income tax

If you are not an EEA citizen, you’re liable for tax at a flat rate of 24% on your rental income, EU/EEA citizens 19% and only they can claim expenses including the costs of a letting agent. https://costaluzlawyers.es/blog/guide-to-taxes-on-rental-properties-in-spain/ 

You can use https://taxadora.com/non-resident-tax-modelo-210/?gclid=EAIaIQobChMI2tiLuvXdgQMV1ep3Ch1XfA3eEAAYASAAEgKBWPD_BwE

To pay Spanish Tax due, via their portal, cheaper than using Spanish accountant, they will also advise you by Email. There is a dual tax agreement with UK, so you are not taxed twice, but you still have to declare HMRC and request tax credit relief, with proof Tax paid in Spain. (Any tax due UK depends on your tax code and tax band).  

 https://www.gov.uk/hmrc-internal-manuals/property-income-manual/pim4702

Thank you for the reply. I wasn't aware of Taxadora and will definitely give them a go so thanks for the heads up. 

The HMRC link sums up perfectly the difficulty I have. Clear as mud, numerous document codes and links that take you down a variety of rabbit holes and/or dead ends. All I want is a form that I need to complete to declare income to HMRC. Is it simple? Do I need specialist help? I don't mind either way. I'm not having a go at you by the way as I've had zero success at trying to get the answer myself and I am genuinely grateful for your response but jeez, it's frustrating. 

"Allowable expenses should be deducted from the income, and any profit then declared to HMRC in your self-assessment return"

https://www.taxchambers.com/news/tax-on-overseas-properties-which-laws-apply/

You do need to declare the income in the UK if you are UK resident . You will pay tax in the UK but will get a tax credit for any spanish tax that is paid . You can email me at [email protected] . I am a qualified UK tax accountant .