What Is PP30? A Thai VAT Return Guide for Calibration Labs

What Is PP30 (ภ.พ.30)?

PP30 is Thailand's monthly VAT return form (ภาษีมูลค่าเพิ่ม แบบที่ 30). Every VAT-registered business must file it by the 15th of the following month — or the 23rd if filing online via the Revenue Department's e-Filing system. For calibration and testing laboratories, PP30 is a recurring monthly obligation if your annual revenue exceeds ฿1.8 million.

Why Labs Must Care About PP30

Penalties: Late filing incurs surcharges of 1.5%/month plus a penalty of 2–5× the unpaid tax
Input VAT refunds: If your Input VAT exceeds Output VAT in a month, you're entitled to a refund — but only if you've filed
Customer trust: Corporate clients and government agencies often verify a supplier's tax-filing history before awarding contracts

The Three Components of PP30

Output VAT (ภาษีขาย)

7% VAT collected from customers on every tax invoice issued that month. Includes calibration services, testing services, and any equipment sales.

Input VAT (ภาษีซื้อ)

7% VAT you paid to suppliers for goods and services used in your business: reference materials, lab consumables, rent, equipment maintenance — all with valid tax invoices as evidence.

Net VAT (ภาษีสุทธิ)

Net VAT = Output VAT − Input VAT

Positive → pay the difference to the Revenue Department
Negative → claim a refund or carry forward to next month

PP30 vs. WHT (Withholding Tax): What's the Difference?

WHT (ภาษีหัก ณ ที่จ่าย) is not part of PP30 but is closely related in lab finance management:

When you provide services: Corporate clients typically withhold 3% WHT from your invoice total and issue you a withholding tax certificate (ภ.ง.ด.53)
When you hire subcontractors: You must withhold 3% and remit it to the Revenue Department via ภ.ง.ด.53 (juristic persons) or ภ.ง.ด.3 (individuals)

WHT credits offset your annual corporate income tax, not your monthly PP30.

How LabSync Automates PP30 Preparation

Output VAT is captured automatically — every tax invoice issued via LabSync uses §86/4-compliant sequential numbering and records the 7% VAT amount
Input VAT from vendor bills — log vendor invoices in LabSync with PDF attachments; the system aggregates Input VAT by month
PP30 Report — navigate to Finance → PP30 Report, select the month, and get Output VAT, Input VAT, and net payable in one view with CSV export for your accountant
File via e-Filing — take the numbers from LabSync into RD Smart Tax, or hand the CSV to your accountant

Common PP30 Mistakes in Lab Operations

Duplicate invoice numbers: Illegal under §86/4. LabSync enforces sequential numbering automatically.
Missing Input VAT records: Labs lose thousands of baht per month in deductible VAT they paid but didn't record.
Late filing: Even one day late triggers a minimum ฿1,000 surcharge.
Wrong VAT rate: Some services (education, certain healthcare) are VAT-exempt — don't charge 7% on those.

Bottom Line

Labs running on a digital management system like LabSync have every number needed for PP30 already in the system — reducing month-end close from 1–2 days of manual spreadsheet work to 15 minutes. Labs still using Excel face the risk of transcription errors, duplicate invoice numbers, and missed Input VAT deductions that add up to real penalties.

To see how LabSync handles PP30 and WHT in practice, start your free 14-day trial — no credit card required.