PAYE Adjustment, UK employment performed in UK and Overseas for non-resident

Hello, I am a UK citizen, but have never been domiciled nor tax-resident in the UK. I have been domiciled and tax-resident in Switzerland for the past 7 years. For the past 2 years I have been an outside IR35 contractor via my UK LTC. I typically spend 30% of my work days in the UK, and 70% work remote from Switzerland. I have a new inside IR35 contract via a UK payroll. I will again work 30% in the UK and 70% remote (approximately). For NI contributions, I know I need to file a form with Switzerland who will then send an electronic notice to PAYE to not deduct NI contributions. My question is on UK income tax withholding within PAYE. From table 6.63 for non-domiciled, I think the applicable section is rows 1&2, column 3. That is my non-UK workdays (ie 70%) are not subject to UK income tax. And per the UK-Swiss double tax treaty, Article 15.1, I will owe income tax on those amounts to Switzerland. I know that I could submit for a tax correction at year end, but don't want to overpay UK tax and fund Swiss tax while I wait for a UK tax refund. I presume there is a form I can submit to modify my PAYE income tax? I have meticulous travel records on my past 30% UK workdays, and also travel receipts for upcoming UK workday trips at 30%. Many thanks if you can point me to the correct form. Regards Swiss Contractor ps. Excellent community forum. Bravo to the HMRC.

ps. here is the link to table 6.63 (scroll down) https://www.gov.uk/government/publications/residence-domicile-and-remittance-basis-rules-uk-tax-liability/guidance-note-for-residence-domicile-and-the-remittance-basis-rdr1 And from further reading, maybe this is the link for guidance on the in-house HMRC staff to make the adjustment, per section 811? But if so, I'm still not clear what form I submit or process I go through https://www.gov.uk/hmrc-internal-manuals/paye-manual/paye13144

pps. Actually, since my Inside IR35 contract is only 4 months, maybe the easiest is to just allow the income tax overpayment, and then submit an "online P50" 35 days after the end for a refund (presuming I don't start a new contract)

Hi SwissContractor,
Your UK employer (or their agent) can contact HMRC to apply for a direction to operate PAYE on an employee's earnings.
If agreed by HMRC, your employer can be authorised only to deduct tax on that part of your employment carried out while in the UK.
Your employer can submit a request here:
Apply for a direction to operate PAYE on an employee's earnings.
You will be required to complete a Self Assessment tax return every tax year, as part of this agreement.
Thank you