A technician finishes cleaning three split aircon units in Nonthaburi at 2 pm. The job took two and a half hours. Total: ฿2,650 including a refrigerant top-up and a replacement capacitor. The technician sends a LINE message to the office, the office sends the invoice that evening, and the customer promises to transfer “tomorrow.” Two days later, a follow-up message. Day four, the money arrives. It does not have to: collecting payment on-site with PromptPay QR takes under four minutes.

That four-day gap is the norm for most Thai install and maintenance businesses. It is not because customers are dishonest — it is because bank transfer after the fact is the default payment path, and defaults have friction. The customer puts it off, the invoice gets buried in LINE, and the follow-up becomes part of the office’s daily workload.

PromptPay QR makes an entirely different approach practical: collect payment on-site before the technician leaves, the same day every job closes.

The Gap Between Job Done and Money Received

Cash flow in field service is a delay problem as much as a volume problem. The work is done; the revenue is earned. But until the money arrives, the business carries the cost — parts, labor, fuel — while the customer holds the invoice.

For a business running 25 jobs a week at an average of ฿2,500 per job, a four-day average payment delay means roughly ฿175,000 in completed-but-uncollected work sitting in the system at any point. Reduce that delay to same-day, and the outstanding balance drops toward zero.

Short payment cycles also reduce write-offs. Invoices that age past two weeks become progressively harder to collect — the customer has moved on, the amount feels less urgent, and follow-up becomes awkward. Payment collected at site before the technician drives off is never at risk of becoming aged receivable.

Why Does On-Site Payment Collection Feel Difficult?

The three obstacles Thai service businesses usually name:

Cash is inconvenient for both sides. Large amounts are unsafe to carry. Change becomes a problem. Reconciling cash across multiple technicians requires manual process that most small offices cannot run reliably.

Card terminals have setup costs and friction. A dedicated payment terminal per technician, linked to a merchant account, is overhead that does not fit a small operation. Many customers also do not carry cards.

PromptPay QR solves both problems. No hardware, no per-transaction setup, no cash handling. The customer pays with the banking app already on their phone. The business receives an instant notification. The cost is near-zero for transactions under ฿30,000.

What Is PromptPay QR for a Service Business?

PromptPay is Thailand’s national real-time payment infrastructure, operated through the banking system and supported by every major Thai bank. Most Thai adults use it daily — via KBank KPlus, SCB Easy, Krungthai NEXT, Bangkok Bank, and every other major banking app in the country.

For a service business, the relevant form is the merchant QR or receive-money QR: a QR code tied to the business bank account. When a customer scans it, they enter the amount and confirm in their app. The transfer reaches the business account within seconds, and both parties receive a notification.

Standard PromptPay transfer fees under the Bank of Thailand schedule are paid by the sender (the customer): ฿0 for transfers up to ฿5,000; ฿2 for ฿5,001–฿30,000; ฿5 for ฿30,001–฿100,000. For a standard ฿2,500 aircon service call, the customer pays ฿0 in transfer fees. For a ฿15,000 install, they pay ฿2. Merchants receiving into a business account typically pay no fee on standard transfers, though banks offering formal merchant QR accounts may charge a small merchant rate — confirm with your bank.

The QR code itself can be:

Static — one QR for the business account, customer types the amount
Dynamic — generated per transaction for the exact amount, eliminating input errors

Static QR is simpler for daily service use. Dynamic QR is cleaner for fixed-price jobs where you want the amount locked.

Setting Up Merchant QR for Service Collection

If your business has a registered bank account, the setup takes under an hour:

Open your bank’s mobile app, navigate to receive / QR payment, and register for PromptPay receive using your company tax ID (เลขที่ผู้เสียภาษี) or registered phone number
Download or screenshot your QR code
Print a wallet-sized copy for each technician, or have them save it to their phone
Run one test transfer from a known account before using it on a job

A Worked Example: Aircon Service in Bang Na

A technician arrives at a residential property in Bang Na for a three-unit aircon clean. Agreed price: ฿2,100 (฿700 per unit). During the visit, the technician notices one unit’s capacitor is starting to fail and offers to replace it on the spot. Customer agrees. Added scope: ฿350 for the part, ฿200 labor.

Final amount: ฿2,650.

Here is how the payment step looks when on-site collection is standard:

Technician updates the job scope on their phone to include the additional work
Customer reviews and signs the digital service report
Technician shows the company PromptPay QR (phone or printed card)
Customer opens their banking app, scans, enters ฿2,650, confirms
Technician’s phone shows an inbound transfer notification
Technician marks the work order “paid” before leaving
Customer receives a LINE message with the service report as a receipt

Total time from completion to payment: under four minutes. The office sees a closed, paid work order before the end of the afternoon.

When On-Site Collection Fits (and When It Doesn’t)

On-site PromptPay collection works well for:

Residential and SME visits where one decision-maker is present
Standard MA visit fees pre-agreed in the maintenance contract
Additional scope approved on the spot during an existing visit

It fits less well for:

Corporate or juristic-person clients on monthly billing cycles with a purchase order process
Large installations above ฿50,000 where staged payments with formal receipts are expected
Government, hospital, or large commercial clients with procurement rules requiring tax invoice before payment

A clear written policy removes the awkwardness at the door: “residential and commercial service visits under ฿30,000 are collected on site; larger installs and corporate accounts follow invoice terms.” Set the expectation in the booking confirmation so neither the technician nor the customer is surprised.

Keeping Field Payments Reconciled and Recorded

When technicians collect payment in the field, the office needs visibility without relying on LINE messages or end-of-day phone calls.

What makes reconciliation clean:

Work order payment status. When a technician marks a job paid in the system — with payment method, amount, and time — the office sees it in real time. No separate notification needed.
Bank transaction matching. Inbound PromptPay transfers appear in the business account’s history with timestamp and sender name. A daily check of transactions against closed work orders confirms everything matched.
Partial payment handling. If a job includes a deposit paid earlier and a balance collected on site, the work order should record both. Two entries, one job, clean reconciliation.

For customers who need a tax invoice (ใบกำกับภาษี), on-site payment does not remove that requirement. Generate the invoice from the closed work order and send it digitally — stamped “paid,” so it is a record, not a chasing tool.

FAQ

What if the customer can’t pay on-site?

Mark the job as “completed — payment pending” in the work order and send an automatic payment reminder for the next day. The difference from the old approach is that the job is recorded in the system rather than floating in a LINE thread, and the follow-up is scheduled rather than remembered. For customers who consistently defer, require on-site payment as a condition of booking the next visit.

Should technicians use the company QR or their personal account?

Always use the company account. Payment into a personal account creates a reconciliation problem, puts business income through a personal bank statement, and means the customer does not see your business name when confirming the transfer. Each technician displays the same company QR — the money flows directly to the business account, and every payment is visible to the office in the account’s transaction history.

Does a PromptPay transfer confirmation replace a tax invoice?

No. The transfer confirmation is proof of payment, not a formal tax document. Customers who need a VAT receipt (ใบกำกับภาษีอย่างย่อ or ใบกำกับภาษีเต็มรูป) still require one, which you generate from the closed work order and deliver by LINE or email. On-site payment simply means the invoice goes out as a record rather than as a collection instrument — a meaningful difference for your receivables position.

A work order that captures scope, signature, and payment in one place makes on-site collection clean and traceable. OnSiteQ’s work orders let technicians update scope, collect signature, and record payment from one screen in the field — so the job closes completely, not in pieces.

Collect Service Payment On-Site with PromptPay QR