When can I apply for tax registration ?

You can register before e-residency. I just went to the tax office, in Victoria in my case, with Passport, marriage certificate if married plus any other proof of incomes and proof of address in Malta / Gozo.  I received my certificate in the post 2 days later. Couldn't have been easier. Not sure what you mean by "tax resident" but you will now need to file a tax return when required.
Ray

Registering for tax and completing a tax return is mandatory once you state your intention to be resident in Malta by applying for your eResidence documentation and ID. You can down the very simple application form on line and post it to the tax office in Malta.
You can take it in to the office in Rabat if you live in Gozo, but it goes to Malta from there in the post anyway!

Ray

Thanks for yours answers Ray and Ray

It's only this application form (https://ird.gov.mt/downloads/other/expa … itable.pdf) ? They don't really need rental agreement or others documents ?

Not when I did mine! But it was over 4 years ago.

Ray

@PatrickJ015

Please see:  https://www.expat.com/forum/viewtopic.p … 51#3450742

Hi Patrick, do you have a social security number (NI) number for malta? If not you can do this online. It usually takes about 5 days to be sent it via email. Then you can go to Floriana to the inland revenue, complete a form and a tax registration number will be given to you hope this helps.

Thanks for yours answers.

@Keziahhopkins : No, I don't. I need this number before apply for a private health insurance ?

You will need the NI number before hand. I'll send you the link so that you can complete the online form. Once you have received the NI number via email you will need to do to Floriana at the inland revenue and they will give you your tax number there and then.

www.socialsecurity.gov.mt

As an Expat you do not need a National Insurance number ( Social Security Number) to register for tax purposes, indeed if you take up residency under the 'Self Sufficiency' option then it is unlikely that you will ever have such a number unless you take up employment.
Your Tax number is usually your ID number from the back of your eResidence card..

All you do is take or post this form to the Inland Revenue office:-  https://ird.gov.mt/downloads/other/expa … itable.pdf

If not employed the space for the Social Security Number is left blank .

Ray