There is a risk that your income may be taxed twice if two countries have the right to tax your income because, for instance:
1) You live in one EU country but work in another (cross-border commuter
2) You are posted abroad for a short assignment
3) You are living and looking for work abroad and have transferred unemployment benefits from your home country
4) You have retired to one country and receive a pension from another
Fortunately, however, most countries have double tax agreements . These agreements usually spare you from double taxation:
Under many bilateral tax agreements, the amount of tax you paid in the country where you work will be offset against the tax you owe in your country of residence.
In other cases, the income earned in the country where you work might be taxable only in that country and exempt from tax in your country of residence.
In order to claim relief from double taxation you may need to prove where you are resident and that you have already paid taxes on your income. Check with the tax authorities what proof and which documents you need to submit.