Does factory rooftop solar add Land & Building Tax?
The answer under the Land & Building Tax Act B.E. 2562 — solar panels are equipment/machinery, not a taxable building/structure — plus the exceptions and edge cases to watch (rooftop vs ground-mount · self-use vs selling power).
In general, installing solar panels on a factory roof does not add Land & Building Tax by itself. Thailand's Land & Building Tax Act B.E. 2562 taxes only land and buildings/structures (สิ่งปลูกสร้าง) — and it does not include machinery or equipment in the tax base. Rooftop solar is by nature power-generating equipment (machinery), not a habitable or usable structure, so it is not valued as a taxable building, and bolting panels on does not automatically raise the building's appraised value. The final classification rests with each local authority (อปท.). The case to watch is ground-mounted solar on a separate plot, which may change that land's "use" category and therefore its tax band. Whether you self-consume or sell the electricity does not affect this property tax (that matters for income tax / energy licensing instead). See BOI solar incentives 2026 and solar tax & depreciation. This is a general summary, not case-specific tax advice — confirm with a tax adviser or your local authority.
Solar panels — a “building” or “machinery”?
The answer hinges on the definition in the Land & Building Tax Act B.E. 2562. A “สิ่งปลูกสร้าง” (building/structure) is a house, building, or other structure that people can live in, use, store goods in, or run industry in. Crucially, this Act does NOT bring machinery and equipment into the tax — unlike the old House & Land Tax, which used to include machinery.
| Item | In the tax base? | Note |
|---|---|---|
| Factory land | Yes | By appraised value & use |
| Factory building/structure | Yes | By appraised structure value |
| Factory machinery | No | Excluded by the Act |
| Rooftop solar PV system | No (generally) | Equipment-like, not a structure |
Bottom line: a factory's Land & Building Tax base = land + the building only, excluding machinery and equipment. Rooftop solar therefore adds nothing to this tax. The final classification is applied by the local authority.
When you're fine — and when to double-check
For most factories putting solar “on the roof for self-consumption,” there is no Land & Building Tax impact. But three situations are worth checking with the local authority or a tax adviser first:
1. Rooftop + self-use — normally no impact
The most common factory case: a rooftop system generating power to cut your own bill. It is treated as equipment/machinery, adds no Land & Building Tax, and does not change the factory building's use classification.
2. Ground-mount on a separate plot — check the land-use category
If solar is installed on the ground on a separate plot (e.g. land previously classed as agricultural or vacant), using it to generate power may shift that land's “use” to commercial/other, which carries a different tax rate from agricultural or residential. Check the use status with the local authority first — this affects the LAND band, not the panels themselves.
3. Large support structures (solar farm / permanent carport) — review case-by-case
Existing rooftop panels are not a new structure. But if you build a NEW structure that people can use — e.g. a permanent solar carport or a canopy building over panels — that structure itself may be assessed as a separate สิ่งปลูกสร้าง (not the panels). Have a tax adviser or the local authority review it case-by-case. See factory solar carports.
This is a general summary as of June 2026, not case-specific tax advice. Final classification and assessment rest with the local authority (อปท.) and can differ by area — consult a tax adviser or your local authority before deciding.
Land & Building Tax rate bands (commercial/industrial)
To show how a factory's tax is computed from “land + building” on the Treasury appraised value, here are the commercial/industrial (the “other use”) rate bands from B.E. 2566 onward (statutory ceiling 1.2% — the ministerial rates in force are lower). Solar panels are NOT part of this base.
| Appraised value (land + building) | Tax rate |
|---|---|
| Up to ฿50m | 0.30% |
| ฿50–200m | 0.40% |
| ฿200m–1,000m | 0.50% |
| ฿1,000–5,000m | 0.60% |
| Over ฿5,000m | 0.70% |
Note: the above are the current commercial/industrial (“other use”) rates and may be adjusted by ministerial regulation — confirm the latest rates and any relief with your local authority. Installing solar does not enlarge this base, which is computed from land + building, not equipment.
Practical guidance for factory owners
Before and after going solar, here is what to do regarding Land & Building Tax:
1. Confirm your system is roof/building-mounted for self-use — this case has virtually no Land & Building Tax impact.
2. If you use a separate plot (ground-mount), check the “land-use category” with the local authority, as it may change the land's tax rate.
3. Keep records showing the solar system is “power-generating equipment/machinery” (EPC quote, single-line diagram, asset booking) to clarify if the local authority queries it.
4. Keep the tax topics separate: Land & Building Tax is a property-holding tax, while BOI privileges, depreciation, and income tax on selling power are different matters. See solar tax & depreciation and factory electricity cost.
CapSolar designs and installs factory solar end-to-end with clear asset documentation and permits, so your finance/tax team books it correctly — backed by 80+ MWp installed across 150+ projects in Thailand. See the full factory solar guide or does a factory need a รง.4 licence for solar.
Author
Compiled by the CapSolar team, led by Frank Lee (Founder), specialists in factory-scale solar EPC and PPA in Thailand. Based on the Land & Building Tax Act B.E. 2562 and Revenue Department / local-administration practice. Last reviewed June 2026. This is not case-specific tax advice.
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