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Depreciation calculator at Revenue Code rates

Quick answer

The Revenue Code caps the annual write-off: permanent buildings at 5%, machinery and equipment at 20%, vehicles at 20% and computers with peripherals at 33.33%. The first year is prorated by the days the asset was held, not taken in full. The calculator is free, needs no sign-up and runs entirely in your browser.

Steps at a glance

  1. Get the cost base right
  2. Pick the asset class
  3. Prorate the first year
  4. Check the result against your source documents before filing.

What to prepare

  • The base amount from a tax invoice, bill or payslip.
  • The rate or income category that applies to the item.
  • Whether the entity is VAT-registered.
  • The tax period or month you are calculating.

Need a scope assessment? Describe the accounting or tax issue, relevant periods and due dates so the checks, required records and responsibilities can be clarified before a meeting.

Discuss your scope

Production machinery may be written off at twenty percent a year, with installation and commissioning costs sitting inside the cost base.

Depreciable cost
100,000 THB
Annual rate for this class
20.00%
Full-year charge
20,000 THB
Monthly charge
1,666.67 THB
First-year charge (12 months in use)
20,000 THB
Written-down value at first year-end
80,000 THB
Approximate years to write off
5

Figures are planning estimates, not tax advice. Have an accountant or CPA review your supporting documents before filing.

Hands comparing receipts beside a calculator and laptop; not Thai tax invoices
Content illustration; not company staff or a client engagement.Kaboompics · Pexels License

Formula used

Annual charge = cost × annual rate · First year = annual charge × months in use ÷ 12

How to use it and file correctly

  1. 1

    Get the cost base right

    Cost includes freight, installation and everything needed to bring the asset into use, but excludes recoverable input tax.

  2. 2

    Pick the asset class

    Match the class to actual use — the maximum annual rate the law allows differs sharply between classes.

  3. 3

    Prorate the first year

    An asset bought mid-year is written off only for the period held; taking a full year in the year of purchase is adjusted on audit.

  4. 4

    Tie it to the fixed-asset register

    The register must show acquisition date, cost, rate, accumulated depreciation and physical location so the asset can actually be verified.

Common pitfalls

  • Items of small value with a brief useful life may go straight to expense, but the policy must be applied consistently across the whole company.

  • Passenger cars of up to ten seats have a tax cost ceiling for depreciation; the excess is not deductible.

  • Book and tax depreciation can differ; the gap is adjusted in the PND.50 reconciliation, not by rewriting the financial statements.

Frequently asked questions

Is land depreciated?

No — land is not treated as wasting, though structures on it are, so the price must be split between land and building at purchase.

Can a lower rate be used?

Yes — the law sets only a ceiling, but once a rate and method are chosen they must be kept for that asset throughout its life.

What if the asset is sold mid-year?

Depreciate to the disposal date, then compare proceeds with the written-down value to book the gain or loss in that year.

Fully written-down assets still in use?

Keep them in the register at a residual of one baht each so they remain countable until genuinely disposed of or written off.

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