 But those in India, Nepal, and Bhutan who work for a salary are supposed to contribute 4% of their base salary or 2% of their gross salary (whichever is higher), whereas for those who had income other than salary, the suggested annual contribution was 0.15% of their net annual income.According to the CTA, the Data Unit of the Department of Finance manages the central database of Green Book holders.The holder of a green book needs to be current on their contributions in order to exercise such rights with the CTA as voting or standing for election, applying for scholarships awarded by the CTA, or for employment with the CTA.