Income tax collection had increased steadily with an average annual growth rate of 19.78 percent as of 1983, but the growth rate averaged jumped to 26.33 percent during the 6th National Economic and Social Development Plan from 1988-1994. Compared to the overall revenue of the government, income tax accounted for 39.03 percent of total revenue in 1983 and rose to 55.92 percent in 1994.
In 1977, during the major tax restructure, the income tax collecting system has been changed from progressive rate to proportional rate system. The Revenue Department also introduced special tax privileges for listed companies, and reduced corporate tax to 30 percent to cut production costs. Value-added tax was also introduced to replace business tax in 1992.
On service quality development, the Revenue Department has improved the workspace layout and tightened up the service process at all service areas. The deposit of VAT form with check payment has been initiated. Personal income tax refund has been fully computerized which resulted in the reduction of refund time to within 60 days. The Revenue Department also has become a member of BAHTNET (Bank of Thailand Automatic High-level Transfer Network) which enables the bank to remit refund right into the bank accounts of the taxpayers by computer. Furthermore, a contract has been signed for the installation of a nationwide computer network at a cost of 1,814.5 million baht. In addition, a project to accept tax returns on computer diskette for personal income tax will be introduced
To develop overall efficiency, the Revenue Department has targeted the promotion of leadership quality personnel as well as the improvement of line management. Decentralization process is under way to give wider scope of authority to officials at district revenue offices. Plans are being drafted to work for a one-spot service concept. The Revenue Department also adopt the business concept of treating taxpayers as important customers.