This excerpt taken from the ATVI 10-K filed Jun 14, 2007.
Cost of living allowance (COLA)
You are eligible for a cost of living allowance. This amount is based on your family size with you on assignment, your annual base salary and on consideration of the goods and services cost differential between your home and host locations (United States vs. United Kingdom).
For the commencement of your assignment, the COLA will be US$47,739.00 on an annualized basis. This allowance will be re-evaluated twice per year and anytime throughout the year if the exchange rate fluctuates by at least 5% over a four consecutive week period. The Company will pay any income tax due on this payment.