Employed in Austria - Living in UK permanently

Hi, I will soon be moving back to the UK - living here permanently (ie more than 183 days in a 12 month period). (Under a Pre-settled Status, switching to Spouse VISA Asap). My Austrian employer wants me keep me employed and will allow me to work remotely form the UK. My only foreign income will be this salary. I understand there is a DTA between the two countries. Am I able to get a Certificate of Residency from the UK to ensure I don't get taxed in Austria (including Social Security taxes) and simply declare the gross salary on a Self-assessment? I understand I can claim a tax credit, but my worry is relating to Social Security I'd be paying in Austria. So wondering if a CoR is the best way to get around that so I only pay UK tax and NI. Thanks

Hi,
As you will resident in the UK while working for an overseas employer, you will be taxable on this income only in the UK, which needs to be recorded in a Self Assessment tax return each year.  
To ensure that no tax is deducted from the income in Austria, you need to request a certificate of residence here:
How to apply for a certificate of residence to claim tax relief abroad
The fastest method is the online service followed by the email form.
Thank you.