Royal Gazette Announcement: Residential Solar Rooftop Installation Now Eligible for Tax Deduction Up to THB 200,000 — Check All Conditions Before Claiming

The key substance of this Royal Decree is to grant a personal income tax exemption for individuals in respect of expenses incurred from installing a solar power generation system on a roof, rooftop terrace, or any part of a building that a person can reside in or use. Such system must be connected to the electricity grid of the Metropolitan Electricity Authority (MEA) or the Provincial Electricity Authority (PEA). The eligible expenses may be claimed based on actual costs, but not exceeding THB 200,000.

Put simply, this measure is a tax incentive for people who want to install a residential Solar Rooftop system, helping to reduce part of the initial investment cost burden. While it is not a direct cash refund, it helps reduce the personal income tax base, making home solar installation more attractive overall—especially for those who already intended to install it to save on electricity bills in the long term.

Those eligible to use this measure are individuals. The law clearly states that it does not include ordinary partnerships, groups of persons that are not juristic persons, or undivided estates. Therefore, if the installation is under an individual’s name and the property is a residential home, it may qualify. However, if the installation is under a business name or another tax structure, it must be considered under a different measure.

Eligible home characteristics

Based on the wording of the law and the Revenue Department’s summary documents, the key point is that the system must be installed on a building used as a residence, whether it is:

• the house roof 

• the rooftop terrace

• any part of the building that people can live in or use

In practice, this therefore covers many types of residences, such as:

• detached house

• semi-detached house

• townhouse

• home office

• a commercial building or shophouse used as a residence

The Revenue Department states plainly that this measure is intended to promote theinstallation of Solar Rooftop systems in residential homes, and it also clearly emphasizes connection to an on-grid electrical system.

How much can be deducted, and how is it calculated?

The deduction is based on actual expenses paid, up to a maximum of THB 200,000, including:

• equipment purchase costs

• system installation costs

If the total cost is THB 120,000, you can claim THB 120,000. But if the total cost is THB 300,000, you can claim only up to THB 200,000, in line with the cap prescribed by law.

It is important to understand that a tax deduction is not the same as receiving a full refund. This is another point people often misunderstand. This measure does not mean the government refunds THB 200,000; rather, it means you can use qualifying expenses to reduce your assessable income for personal income tax purposes, up to THB 200,000. The actual benefit therefore depends on each person’s tax bracket.

Simply put, people with different tax liabilities will see different levels of tax savings, even if they install systems at similar prices.

To claim the solar tax deduction, it doesn’t end with simply having a quotation and installing panels on the roof—you must meet several key conditions, each of which directly affects eligibility.

1. The system must be installed on a residential home

The law clearly states that it must be a system installed on a roof, rooftop terrace, or any part of a building that a person may occupy or use. Therefore, it must primarily fall within the scope of a “residential home,” not an installation outside that scope or described too broadly.

2. It must be an On-Grid system

The Revenue Department has clearly emphasized that it must be a system connected to the electricity grid (On-Grid) of:

• Metropolitan Electricity Authority (MEA)

• Provincial Electricity Authority (PEA)

This is why homeowners should ask the provider from the outset whether the system to be installed meets this condition, because not all solar systems are the same type.

3. An e-Tax Invoice is required

The documentation requirement is very important because Section 5 of the Royal Decree stipulates that payment must be made to a VAT-registered operator, and you must receive a tax invoice issued electronically, or an e-Tax Invoice.

In practice, this means that even if the installation is completed, if the tax documents are incorrect, you may not be able to claim the deduction. Therefore, before deciding to hire an installer, you should clearly ask whether:

• The shop or company is VAT-registered

• They can issue a full-format e-Tax Invoice

• The expense items on the tax invoice are clearly itemized

4. The deduction can be claimed once, and for no more than one system

This measure does not allow repeated claims. Revenue Department documents clearly state that the deduction can be claimed once, and for no more than one system, throughout the duration of the measure.

That means if you plan to install a system, you should define the system design and budget clearly from the start, because this measure is not designed for claiming the deduction in multiple rounds.

The law stipulates that you may claim the personal income tax exemption once in the tax year in which the system is successfully connected to the electricity grid, not solely based on the year installation begins or the year the first installment is paid.

Why is this important? Because in real life, installing a solar system may not be completed in a single day. There are site surveys, design agreement, document submission, installation, and coordination for connection with the electricity authority. If a homeowner plans their taxes but does not allow for the actual connection timeline, they may end up claiming the benefit in a different tax year than expected.

Therefore, anyone serious about tax planning should keep all documents complete, including:

• Contract

• Tax invoice

• Proof of payment

• Evidence of successful system connection

The Royal Decree stipulates that it shall take effect from the day following its publication in the Royal Gazette. Meanwhile, Krungthep Turakij reported that the document was published on 2 March 2026 and applies to expenses paid from 3 March 2026 to 31 December 2028.

The Revenue Department also summarized the same timeframe: the Solar Rooftop measure for residential homes applies from the day following the date the law is published in the Royal Gazette until 31 December 2028.

Summary of key dates you should know

• Measure starts: 3 March 2026

• Measure ends: 31 December 2028

• Claim the benefit in the tax year in which the system connection is successfully completed

Can it be claimed together with other measures?

The answer is no, if it is the same expense. This is because Section 5 of the Royal Decree states that expenses for which a tax exemption is claimed under this decree must not be used to claim a tax exemption under any other Royal Decree or Ministerial Regulation, whether in whole or in part.

For those who are already in talks with an installer, or have just started researching, here is a checklist you should review before signing the contract.

Confirm the system details

• Is it an on-grid system?

• Can it be connected to MEA or PEA?

• Does the installation on a residential home meet the requirements?

Check the seller or installer

• Are they registered for VAT?

• Can they issue an e-Tax Invoice?

• Are equipment costs and installation fees clearly itemized?

Check your tax-benefit plan

• In which tax year will the system connection be completed?

• Do you have all required documents for filing your tax return?

• Are you planning to claim any other tax benefits that overlap with the same expense?

Although this measure may seem purely tax-related, the rationale behind the law clearly reflects that the government aims to promote the use of solar energy in the household sector and improve energy efficiency, helping Thailand move toward energy sustainability, including the goals of carbon neutrality and net-zero greenhouse gas emissions.

This measure is suitable for those who are installing a residential Solar Rooftop system and want to claim the tax deduction correctly, subject to the following key conditions:

• The claimant must be an individual taxpayer.

• It must be installed on a residential home.

• It must be an On-Grid system.

• It must be connected to MEA or PEA.

• An e-Tax Invoice is required.

• The deduction is based on actual expenses, capped at THB 200,000.

• The right can be used once only, for no more than one system.

• The right must be claimed in the tax year in which the system connection is successfully completed.

• Applicable to expenses incurred from 3 March 2026 to 31 December 2028.

Ultimately, for homeowners who already intend to install solar, this measure is a fairly clear form of support because it makes the overall investment look more worthwhile. However, just as important as the deduction cap is preparing the documentation and selecting an installer that meets the requirements from the outset, because the tax benefit will only actually apply when every detail fully complies with the legal criteria.

References:

• Krungthep Turakij, news: “Royal Gazette announcement: Solar panel tax exemption, deduction up to 200,000—check the conditions!”

• The Revenue Department, document: “Tax measures to promote the installation of Solar Rooftop systems in residential homes”