There is a lot of bullsh*'t and other comments but little clarification. Personally will also not go in a debate on this as I believe there are little to no tax consultants on this forum and every situation is unique and sometimes complex
1) if you don't live anywhere fixed and don't have a residence, some institutions consider you to be a permanent resident in the country of citizenship hence might exchange all information to there
2) tax authorities if they challenge you will ask for proof as mentioned in the post before. Still having ties with Germany such as bank accounts which are registered on a German address and that receive regularly income can get challenged. As in many Western countries in Europe your centre of vital intrest can make you a resident, even you don't spend much time there.
3) every situation is different and living in different countries can become very complex tax wise IF any of those countries start to investigate your income for any reason. Many people have opinions which are what they are.. opinions. How many have had here tax authority investigations? I speak from personal experience being involved in a tax investigation (involving tax authority raids on several locations) at present in three countries and might further escalate to other countries. I definitely don't know all the rules and implications but some things learned :
- break all ties with European country of citizenship if you don't want to get challenged. It's ok to still have a bank account or credit card as long as it's infrequently used and definitely no regular income or outgoing, preferable not.
- make sure if you stay over 6 months in a country, it is a country only taxing on local sourced income and not worldwide income, or you can also get challenged there (each country has its own tax rules, make sure you understand them well and the risk of having them enforced). The risk of being investigated is low if amounts are low, but anything (mostly unexpected) can trigger an investigation
- keep most of your assets out of any country you believe that can be a potential risk. Chose countries that are easy on transferring larger funds, multi currency etc
- have a residence, preferable in a country that doesn't tax on worldwide income, is not tax aggressive and preferable doesn't exchange information through CRS. Use this residence to register bank accounts / companies in other jurisdictions
GENERALLY (this is not conclusive) , individuals are deemed to be resident:
- if they have a dwelling in Germany that they use, or that is at least available to them (irrelevant if rented or owned – even a room at a friend’s house could be enough if always accessible), or
- if they have an habitual abode in Germany. This can be assumed if the individual is physically present in Germany for more than six months in any one calendar year, or for a consecutive period of six months over a year-end.
Objective circumstances are decisive. Nationality is not, in itself, a criterion for determining residence or tax liability. Also, registration with the German (tax) authorities is only an indicator.
Where an international assignee has a residence in two or more countries, the employee is deemed, for application of a double tax treaty (DTT), to be a resident of the contracting state in which the employee has a centre of vital (personal and economical) interest
This is not entirely correct, since you will still need to receive your income on a bank account, which has a residential address tied to it and can result in tax implications.
Chances are very low to have issues with this set up if the income is limited and you cut most ties with country of citizenship.
Without a residence it is very hard to open a bank account and if you are unlucky and get challenged it's helpful to have proof that you have at least some fixed residence with long term rental contract etc