BANGKOK, THAILAND – A new royal decree granted income tax relief of up to 200,000 baht for installing rooftop solar power systems, effective until 31 December 2028.
Royal decree and entry into force
The measure carried the official title Royal Decree Issued under the Revenue Code on Tax Exemption (No. 805) B.E. 2569 (2026) and took effect the day after its publication in the Royal Gazette. The relief was therefore tied directly to the formal announcement in the official journal.
As its legal basis, the decree cited Section 175 of the Constitution and Section 3(1) of the Revenue Code in its amended form. The provisions were framed as a specific exemption within the existing tax law framework.
Up to 200,000 baht deduction – what exactly is covered
The decree allowed natural persons to deduct assessable income equal to the actual costs paid for the purchase and installation of a solar power generation system on a roof, roof terrace or other usable part of a building. The benefit applied only where the expense related directly to such a system.
A condition was that the system had to be connected to the grid of the Metropolitan Electricity Authority (MEA) or the Provincial Electricity Authority (PEA). The total amount of tax relief was capped at a maximum of 200,000 baht per eligible case.
One system per household – and only one claim
According to the decree, the incentive applied solely to the costs of a single solar power system, paid between the date the decree entered into force and 31 December 2028. Multiple systems within the same household were not covered.
The deduction could be claimed once only, in the tax year in which the grid connection of the system was successfully completed. This timing rule linked the tax benefit to the technical commissioning date.
Strict cut-off dates – no retroactive claims
For the 200,000-baht relief, the decree set an eligibility period from 3 March 2026 to 31 December 2028. Payments or connections outside this window were not recognized for the incentive.
The summarized conditions explicitly excluded retroactive claims for systems whose installation or grid connection had been completed before the cut-off date. Taxpayers with earlier systems were therefore not entitled to apply under this scheme.
Technical criteria – on-grid only and maximum 10 kWp
The programme supported new installations configured as on-grid systems, with the option to add a battery. Off-grid arrangements were not included in the described support.
Installed capacity was limited to a maximum of 10 kWp per household. In addition, the applicant had to be named both on the electronic tax invoice and as the holder of the electricity meter, aligning fiscal and utility records.
E-invoice requirement and ban on multiple tax benefits
Payments had to be made to a value-added tax registered provider, and an electronic tax invoice (e-tax invoice) compliant with the Revenue Code was required. This documentation served as the key proof for claiming the deduction.
Costs deducted under this decree could not be used simultaneously for other tax exemptions. They also could not be channelled into activities already enjoying corporate income tax exemptions under laws on investment promotion, the competitiveness enhancement of target industries or in the Eastern Economic Corridor (EEC).
Extra incentive for efficient machinery and energy saving
Beyond solar, Section 4 of the decree created a separate income tax exemption for certain private income as well as for companies and juristic partnerships investing in high-efficiency machinery or energy-saving technology. This broadened the scope of energy-related incentives.
Under this provision, assessable income equal to 50% of the portion of income associated with the relevant expenditure could be exempted. The products involved had to carry a 5-star efficiency label certified by DEDE and EGAT.
Who enforces the rules – and who can tighten them
According to Section 6, the Minister of Finance was responsible for implementation of the decree. Oversight of compliance and application lay with this ministry.
At the same time, the Director-General was empowered to set additional requirements by notification. This left applicants needing to keep a close eye on documentation duties and any further clarifications issued by the revenue authorities.