A tax reform roadmap, which cuts the maximum personal income tax rate and tax deductions and allowances and includes a proposed housing and land tax, is expected to be completed by November.
The top bracket for personal income tax will be proposed by the Finance Ministry's committee tasked with tax reform, and it plans to cut it to 28% from 35%.
The ceiling for taxable income will also be increased from more than 4 million baht now, said Kitipong Urapeepatanapong, a member of the 15-person committee, without providing details on other tax rates.
The current personal income tax structure sees taxable income of 150,000 baht or lower exempted, from 150,000 to 300,000 charged at 5%, from 300,000 to 500,000 charged 10%, from 500,000 to 750,000 charged 15%, from 750,000 to 1 million charged 20%, over 1 million up to 2 million charged 25%, over 2 million up to 4 million charged 30% and over 4 million levied 35%.
The proposal to lower personal income tax is aimed largely at discouraging some individuals from filing corporate income tax claims instead of personal income tax, said Mr Kitipong, who is also chairman of Baker & McKenzie's Bangkok branch.
He said some people paid corporate income tax instead, as the rate was far lower.
The corporate income tax rate is 20%, although the rate is closer to 28% if dividend-related tax is taken into account.
However, Mr Kitipong said the committee would also propose lowering deductions and allowances for personal income tax so it was fairer for all taxpayers.
The Finance Ministry earlier said the Revenue Department would set up a working panel to consider cutting either the ceiling tax deduction of 500,000 baht for investment in long-term equity funds (LTFs) or the overall deduction to 800,000 baht a year.
The tax incentive for investment in LTFs will come due at the end of next year.
Taxpayers can deduct contributions of up to 15% of their taxable income or 500,000 baht, whichever is lower, for investment in LTFs.
However, money invested in LTFs must be held for at least five calendar years.
Mr Kitipong said if the Finance Ministry intended to change the Revenue Code, which has been used for 70 years, it should based on Singapore's due to its transparency and clarity.
The committee will also propose a ceiling reward for whistleblowers on customs tax fraud of 10 million baht each, down from an unlimited amount now.
A shake-up of the appeals committee for tax issues is another planned measure, replacing state officials with third parties to create fairness.
Board of Investment tax privileges also need changing, Mr Kitipong said.
He said it was necessary to encourage all people regardless of income to file tax claims so the Revenue Department had them in their database.
"If we don't proceed with tax reform, it will be impossible to do so in the future," Mr Kitipong said.
"Previous elected governments failed to do anything even when one party had a majority vote."