The Common Reporting Standard (CRS) is a worldwide information-gathering and reporting requirement for financial institutions, to help fight against tax evasion and protect the integrity of tax systems.
Under the CRS, we are required to determine where you are "tax resident" (this will usually be where you are liable to pay income or corporate taxes) and give national tax authorities information on those customers that are tax resident/paying taxes outside the country where they bank. They may then share this information with the tax authority of the country (or countries) where you are tax resident.