No. You are only considered as a tax resident in Portugal after you change your address in your NIF to a Portuguese address or stay in Portugal for more than 183 days. The NIF you obtain for the Portuguese Golden Visa is a NIF as a non-resident, which means that you will have a taxpayer number in Portugal, but someone will represent you before the Tax Authorities in Portugal for mail purposes.
Does it mean that my tax residency is in Portugal if I request a taxpayer number?
I was told that the first step to applying for a Golden Visa in Portugal is to apply for a local taxpayer number. Does this mean that I automatically transfer my tax residency to Portugal? What are my options if I do not want to transfer my tax residency?
It’s not correct that your tax residency is in Portugal if you request a taxpayer number. You can apply for a taxpayer number and be resident abroad.
As you correctly stated, the first step to applying for a Golden Visa in Portugal is indeed to apply for a taxpayer number (NIF) before the Portuguese Tax Authorities. That, however, does not mean that you will automatically transfer your tax residency to Portugal since you can apply for the taxpayer number (NIF) as a non-resident. As a Golden Visa holder, you can keep your tax residence outside Portugal, as long as you don’t spend more than 183 days each year in Portugal. If such occurs, you will become a tax resident in Portugal.
No, your tax domicile does not change automatically. Usually, you request a taxpayer number (NIF) using your home country address, hence, you are enrolled as a non-tax resident. This is sufficient for your Golden Visa application.