Reasons for using an offshore bank include:

Asset Protection

Generally offshore banks are used as a form of asset protection, which may be an advantage for those resident in areas where there is a risk of political turmoil who fear their assets may be frozen, seized or disappear. Interest is generally paid by offshore banks without tax deducted, which is an advantage to individuals who do not pay tax on worldwide income. However, anyone subject to US income tax is required to declare on penalty of perjury, any offshore bank accounts they may have.

Interest

Some offshore banks may operate with a lower cost base and can provide higher interest rates than in the home country due to lower overheads and a lack of government intervention.

Contractors

If you are a contractor who spends most of your time working overseas or for foreign companies, it can be advantageous to have an offshore bank account that you can use to handle all your income and investments, regardless of where you normally live.