Delivered but the Customer Won't Sign Acceptance, So You Can't Invoice: How to Draft Delivery and Acceptance Terms

The work is finished and delivered, yet the signed acceptance certificate has not come back. The customer's accounts team says it cannot take your invoice without one, the inspector is in meetings or has moved on, and your money is stuck behind work that is already done. This is common in construction, made-to-order manufacturing, system development and any service delivered as a finished result, and it is best fixed when the contract is drafted, not when you are chasing payment.

This guide explains the rules that decide when remuneration falls due and how to draft delivery, acceptance and invoicing as one connected chain. It builds on what you may have read in retention money that is not returned and unpaid invoices from business customers. If a large customer has just sent you its contract, read checking a large customer's contract before signing first.

The short answer

A contractor can invoice with confidence when the contract says when acceptance occurs, who has authority to inspect, how many days the customer has, how defects must be notified, and what happens if the customer is silent, and when the contractor can show that it delivered and followed that process. If the contract says only "payable after acceptance", a customer who will not inspect controls the timing of payment alone.

The law Civil and Commercial Code Section 587 defines hire of work as a contract in which the contractor agrees to do work to completion and the employer agrees to pay remuneration for the result. Section 602 provides that remuneration is not payable until the work is accepted, and where delivery in parts is agreed with remuneration for each part, it is payable on acceptance of that part. Section 598 deals with the effect of accepting the work without reservation on liability for defects. Sections 600 and 601 deal with the period of liability and the limitation period for defects. Section 207 treats a creditor as in default when it refuses a performance the debtor tenders. Section 369 applies to mutual contracts and allows one party to withhold its own performance while the other has not performed, which customers often invoke when they refuse to pay.

Our practical view The law does not set an acceptance procedure, so the contract must. Do not leave "acceptance" as something the customer can do whenever it likes. Turn it into a process with a deadline, a named person responsible, an exit when the customer is silent, and a rule that separates minor defects from the right to be paid. The outcome in a dispute still depends on the wording, the circumstances and the court, so we cannot promise a result in advance.

Hypothetical example A stainless-steel workshop in Khon Kaen (the "workshop") makes and installs a commercial kitchen for a mid-sized hotel. The contract says only "the balance is payable after acceptance of the work". The workshop finishes and hands over, but the hotel's chief engineer is on long sick leave, nobody signs the acceptance certificate, and accounts will not take the final instalment invoice, 30 percent of the contract price. The hotel has been using the kitchen for three weeks. We use this case below.

1. When does remuneration fall due in a hire-of-work contract?

Under Section 587 the employer pays for the "result" of the work, and Section 602 ties payment to acceptance. So the contractor should not assume it can invoice the moment the work is finished, but nor should the customer be able to say it has not accepted without giving any reason. Courts tend to ask two things: was the work completed as agreed, and has the employer accepted it or should it have accepted it by now.

• Contracts in milestones If delivery is in parts with remuneration for each part, Section 602 makes each part payable on acceptance of that part. State clearly what each milestone delivers and what is paid.
• Contracts that are not pure hire of work Monthly services, system maintenance or mixed sale-and-installation contracts may be different, so rely mainly on the contract terms. See MSA and SLA monthly service contracts and software development contracts and source code.
• Retention money If the contract lets the customer hold back part of the price, invoicing is separate from release of the retention. See the retention money guide.

2. What if the customer refuses properly delivered work?

Section 207 says that if the debtor offers performance and the creditor does not accept it, the creditor is in default. In hire of work the contractor is the debtor for delivery and the employer is the creditor for acceptance. If the contractor properly tenders work that conforms to the contract and the employer refuses without good reason, the contractor may argue that the employer is in default. To succeed on that point you must be able to prove that

1. the work tendered conformed to the contract and did not still have significant defects;
2. you asked the employer to accept it within the time and by the method agreed; and
3. the employer refused or stayed silent without a credible reason.

On the other side, the customer may invoke Section 369: since the contractor has not fully performed, the employer need not pay yet. That defence works only to the extent that the work is genuinely incomplete. If the defects are minor and can be fixed, a court may not allow the customer to hold the whole sum, but each case turns on its facts.

3. How should the contract link delivery, acceptance and invoicing?

The core is a single chain in which every step has evidence and a deadline.

In the hypothetical, the workshop should have named the chief engineer or a person the hotel appoints in writing as inspector, a 7-working-day inspection period, and the general manager as a fallback recipient if the chief engineer is absent. A named alternate prevents the case where the only inspector disappears.

4. How far does a "deemed acceptance" clause go?

A clause saying that if the customer does not give written notice of defects within N days the work is deemed accepted is the main tool that frees the contractor from waiting for a signature. Section 598 is consistent with the idea: if the employer accepts the work without reservation, the contractor is released from liability for defects, except defects that could not be seen at the time of acceptance or that the contractor concealed.

To give the clause weight:

• Write it plainly and do not bury it in general conditions. The customer's authorised person should be aware of it before signing.
• Make the period reasonable for the size of the work, not so short that real inspection is impossible.
• Make sure the named inspector is actually notified by the channel the contract specifies, such as a stated email address or an agreed LINE account.
• Do not cover hidden defects. Avoid drafting that makes the employer give up every right, as that may be challenged or conflict with good faith under Section 5 and interpretation under Section 368.
• Real-world use. State that use for testing is not acceptance, but that ordinary commercial use after the inspection period has run is an indication of acceptance.

If the customer is a consumer, terms that cut back rights face closer scrutiny. And where wording is doubtful, Section 11 reads it in favour of the party who would bear the obligation, so draft clearly from the start.

5. Partial acceptance, milestones and the punch list

Do not let a single minor defect postpone acceptance of a whole package. The workable approach is to separate the "criteria that must be met for acceptance" from the "punch list".

• Acceptance criteria Define what must actually work for its purpose, for example that the kitchen operates according to the drawings and the water system has no leaks.
• Minor defects Items such as surface scratches or uneven silicone go on the punch list with a date for fixing.
• A small hold-back If agreed in advance, the customer may hold back a proportion that is reasonable against the value of the outstanding items, not the whole instalment, and release it when they are fixed.
• Milestone acceptance Issue a separate acceptance record for each milestone so that Section 602 can apply to each accepted part.

Sample wording for a handover record (adapt to the actual job)

Handover and acceptance record No. ____
Contract No. ____ Milestone ____ Delivered on ____ Delivered by ____ Inspector ____ (per contract clause ____)
1) Work delivered: ____
2) Result: [ ] Accepted  [ ] Accepted with punch list attached  [ ] Not accepted (reasons must be given in writing)
3) Punch list (minor defects that do not affect use): ____
   To be fixed within ____ days. Amount held back ____ (if any), released when fixed.
4) The contractor may invoice this milestone from the date of this signature.
5) If written reasons for non-acceptance are not received within ____ working days of delivery, the work is deemed accepted under clause ____.
Signed: Deliverer ____ Inspector ____ Date ____

6. Delivery evidence: what to keep so you can prove it

When a dispute arises, the contractor has to prove what was delivered, when, to whom, and how the customer responded or stayed silent.

• Delivery note or handover minutes Have the recipient sign and date, and make sure the recipient is the inspector named in the contract.
• Photos and video Record the installed or delivered work showing date, time and place.
• Emails and LINE Send the notice that the work is ready for inspection to the inspector and the alternate, and keep screenshots and an export of the chat. Under the Electronic Transactions Act B.E. 2544 Section 7, a message cannot be denied legal effect merely because it is in electronic form, but its reliability must still be proved.
• Site entry records Sign-in books, gate passes or the installer's daily reports.
• Evidence of use If the customer has started using the work, for instance the hotel operating the kitchen, record it, because it shows the customer has already benefited.

For extra work ordered through chat messages, which often gets mixed into delivery conversations, see extra work ordered via LINE and variation evidence.

7. A follow-up timeline when the customer has not accepted

The example below assumes a 7-working-day inspection period. Adjust it to your contract.

Sample notice (adapt to the actual job)

Dear ____ (inspector under contract clause ____)
Re: End of inspection period and deemed acceptance, milestone ____
We delivered the work on ____ and notified you by email on ____ that it was ready for inspection. The ____ working-day inspection period ended on ____.
We have not received a written list of defects. Under clause ____ of the contract the work is therefore deemed accepted.
If you believe there are defects, please send the items and reasons within ____ working days, failing which we will proceed under the contract.
Invoice No. ____ is attached, due on ____.

8. What to do when acceptance is unreasonably withheld

If the customer does not respond even after the timeline above, proceed in order.

1. Check the contract and the evidence first. Does it include a deemed-acceptance clause? Is the person you notified the one the contract names? Could the work have significant defects the customer could rely on?
2. Send a formal demand letter summarising the delivery date, the notice date, the inspection period, the deemed-acceptance clause and the payment deadline. Use the demand letter service if you want a lawyer to prepare it.
3. Cite the consequence of default. You may state that the employer refused acceptance without good reason under Section 207, but avoid threats or claiming more than your rights.
4. Keep a way to negotiate. Offer a joint inspection or a joint handover on site, which is often faster than suing.
5. Consider a claim. If the customer still does not pay without a credible reason, you may have to sue for the remuneration and default interest. The result depends on the contract, the delivery evidence and the quality of the work.

Meanwhile, do not deliver further work or start the next milestone unpaid unless you agree in writing, and if there is retention money or a guarantee, check its release terms in retention money that is not returned.

Where the customer deducts a penalty or damages from the price, which often follows late acceptance, see a customer deducting a penalty or damages from payment.

9. What the contractor must watch on its own side

Drafting to be able to invoice does not release you from liability for defective work. Under Section 600 the contractor is liable for defects that appear within one year of delivery unless the contract provides otherwise, and Section 601 bars an action after one year from the time the defect was discovered. Check the detail for your type of work, since building work may have different periods, and set the warranty period clearly in the contract. A contractor that delivered incomplete work or work with significant defects should not rely on a deemed-acceptance clause to cover them.

10. Checklist before delivery and invoicing

In the contract

• Name the inspector by name or position, with an alternate
• Set the inspection period in working days and say when it starts
• Require defects to be notified in writing with items and reasons
• Set the time to fix defects and re-deliver
• Write the "deemed accepted" clause for silence after N days
• Separate punch-list items that do not affect use from the acceptance conditions
• State when you may invoice and how many days the invoice takes to fall due

At delivery

• Use a delivery note or acceptance record signed by the inspector named in the contract
• Take photos or video with date and time
• Email the ready-for-inspection notice to the inspector and the alternate
• Keep LINE screenshots and export the full chat

After delivery

• Put the follow-up dates from Section 7 in a calendar
• Record the defects the customer reports and the dates they are fixed
• Send the deemed-acceptance letter when the deadline passes
• Issue the invoice citing the acceptance date or the deemed-acceptance date

Further reading

• Retention money that is not returned — when the customer still holds money after accepting the work
• Unpaid invoices from business customers — following up and demanding payment after invoicing
• MSA and SLA monthly service contracts — when the service is monthly and has measured targets
• Software development contracts and source code — system acceptance and source code handover
• Checking a large customer's contract before signing — review the acceptance and payment terms before agreeing
• Quotations and purchase orders with conflicting terms — when two documents set different acceptance terms
• Extra work ordered via LINE — keeping evidence of extra work and rework

Good acceptance terms have a named inspector, a deadline, a written defect list and a clear result when the customer is silent, so that you can invoice without waiting on anyone.

We help draft and review contracts, delivery notes, acceptance records, and notices or demand letters so that delivery, acceptance and invoicing fit together. For an initial consultation, call +66 92 254 2045 or send us the details. See also contracts and business documents.

This guide is published by Suwanvara Law Firm — a Khon Kaen law firm established in 1986. General information only, not legal advice on a specific matter.