A standard deduction of 50%, with a limit of THB 100,000, is permitted in respect of income from employment. Business deductions are not available against employment income.
Donations to educational institutions, public health care facilities, approved charities, and the Technology Development Fund for Education are deductible in the amount donated but not exceeding 10% of net income after all allowances and deductions.
A double deduction is allowed in respect of donations to support certain educational programmes and cultural activities.
In addition, donations to various educational institutions or sports entities from 1 January 2016 to 31 December 2018 are allowed a double deduction.
Life insurance premiums
Life insurance premiums, in an amount not exceeding THB 100,000, paid by a taxpayer on one's own life are allowed as a deduction, provided that the insurance policies are for a minimum period of ten years and the insurer is carrying on a life insurance business in Thailand. The amount of any embedded health or accident premium will not be deductible, except as noted below. Moreover, if the policy includes a savings plan that provides an annual return to the policy holder exceeding 20% of the annual premium, the entire premium will be non-deductible.
Qualified pension life insurance premiums paid to a Thai insurer are available as a deduction in the amount not exceeding 15% of total assessable income with a maximum of THB 200,000. However, this allowance, together with the contribution to a registered provident fund, the civil servant pension fund, the welfare fund, and the investment in a retirement mutual fund, may not exceed THB 500,000 in the same tax year.
In addition, the amount paid, up to a maximum of THB 10,000, for a life insurance premium for the taxpayer's spouse who does not earn income is also allowed, provided the marital status exists throughout the tax year.
Health insurance premiums
A health insurance premium, up to a maximum of THB 15,000, paid to a life or non-life insurance company in Thailand by a taxpayer for one's own health is allowed as a deduction. However, the deduction for this premium together with the above life insurance premiums paid cannot exceed THB 100,000 in total.
A health insurance premium, up to a maximum of THB 15,000, paid to a life or non-life insurance company in Thailand for the taxpayer's parents or the parents of the spouse of the taxpayer is allowed as a deduction.
Expenses for antenatal care and child delivery
A deduction of up to THB 60,000 for each pregnancy is allowed for expenses paid by the taxpayer or spouse for antenatal care and child delivery. If the expenses for each pregnancy are not paid in the same tax year, the amount actually paid in each tax year is allowed, but in total no more than THB 60,000.
Mortgage interest expenses
Mortgage interest incurred for the purpose of purchase or construction of a residential building in Thailand may be deducted up to a maximum of THB 100,000.
Retirement mutual fund (RMF) contributions
A contribution to an RMF is deductible in an amount not exceeding 15% of assessable income received that is subject to income tax, with a maximum of THB 500,000 in any tax year. However, if the taxpayer also has any of the contributions noted above under qualified pension life insurance, they must be included in the THB 500,000 limit.
Long-term equity fund (LTF) investments
A contribution to an LTF is also deductible in an amount not exceeding 15% of assessable income received that is subject to income tax, with a maximum of THB 500,000 in any tax year, provided that the investment units are held for at least seven calendar years, except in the case of incapacity or death.
Social Security Fund contributions
The contribution to the government's Social Security Fund is also deductible.
There is a personal allowance of THB 60,000 each for the taxpayer and the taxpayer’s spouse (provided that the taxpayer's spouse does not file one's own return). There is also an allowance of THB 30,000 for each child and an additional THB 30,000 for the second child onwards born in or after 2018. Moreover, an allowance for parental care of THB 30,000 per parent is deductible. A non-resident is allowed deductions for spouse, children, and parent only if they are resident in Thailand.
In addition, a deduction is allowed for the care of disabled or incapacitated family members of THB 60,000 per person and for the care of a disabled or an incapacitated person other than a family member of THB 60,000 in total.
In the case of individuals engaged in business or the practice of a profession, all expenses exclusively incurred for the purpose of the business may be deducted, subject to the various rules prescribed in the Revenue Code. Alternatively, a standard deduction ranging from 10% to 60%, depending on the nature of the business, may be applied.
For individuals, the carryforward or carryback of losses is not permitted.