tax haven 
noun
A country or independent area where taxes are levied at a low rate.The tiny principality of Liechtenstein has managed to transform itself from a poor farming country into a wealthy tax haven....
- Stafford originated the idea of a financial tax haven for Dublin, though it was later regarded as the brainchild of Dermot Desmond.
- As Bank of Ireland's operations in the Jersey tax haven come under close scrutiny by the Revenue Commissioners, exposure of its business practices should be a source of deep embarrassment to management.