Hi Danny Burns
Article 18 of the double taxation agreement advises that residents of Italy, who have non government UK pensions/annuities are taxable only in Italy on their non government UK pension/annuities.
To request that no tax is deducted from your UK pension, you will need to download and print off the form DT individual here
Double Taxation: Treaty Relief (Form DT-Individual.
Once you have declared your pensions/annuities sources, including state penions; please send the signed and dated form to your local Italian tax office.
The Italian authorities will validate the form to confirm you are an Italian resident and taxable on those pension in Italy and return the form to you.
Please then send the validate form to HM Revenue and Customs Pay As You Earn and Self Assessment BX9 1AS, United Kingdom.
With a validated form, we can authorise your UK pension provided to stop deducting tax and repay any tax deducted in this tax year.
We can send you a cheque for any overpaid tax up to the last 4 tax years.
Thank you