0T vs. NT tax code for overseas ex-employee restrictive covenant payments?

My former employer is going to be paying me monthly because of a non-compete agreement. My notice period has ended and they have already issued me a P45 statement -- I am not an employee anymore. I have no other sources of income (in the UK or abroad). I have left the UK and HMRC have given me an NT tax code ("NTX" to be precise). However, my former employer is stating that they are obligated by law to use a 0T tax code for all upcoming payments. They are citing https://www.gov.uk/employee-leaving which corroborates their statement, but I am worried that page might be incorrect (perhaps whoever wrote that page forgot to consider people who move abroad?). Which tax code should my former employer be using in this situation? Keep using 0T or switch to NT? Thank you in advance!

Hi
As you are no longer a live employee the employer must use the 0T tax code as HMRC cannot issue a correct tax code.
You will need to speak to personal tax if you believe you have overpaid tax.

Do things stand differently if HMRC issues code NT before the P45 is issued? Could then the company continue issuing post-employment post-P45 non-compete payments under an NT code?

Hi,

Once an employee is made a leaver the employer would use the 0T tax code, as by that point the employer and HMRC do not know the correct tax code to use. As stated previously, the employee can contact our Income Tax team to check if they have overpaid.

Income Tax: general enquiries

Thank you.