Declare as tax resident in bank account application

Dear Sir / madam, If I have stayed in the UK for 120 days up to today and plan to continue staying here for more than 5 years in the future, I would like to know if I can open a bank savings account and declare myself as a tax resident. Do I need to wait until I have stayed in the UK for more than 183 days? Thank you.

Hi,

You would need to speak to the bank about this, as opening a bank account is banking matter and not a tax matter.  
You can look at the guidance at RDR3 and take the statutory residence tests.  

RDR3 Statutory Residence Test

This will allow you to determine if you are UK tax resident for the whole tax year.
Thank you.