Note
Stage Sign-Off Before the Billing Date
The work is finished. Materials are installed and your team has moved to the next section.
Nothing can be invoiced until the main contractor’s engineer has come, inspected the scope, and signed the acceptance document.
If that sign-off does not happen before your billing cutoff date, the invoice waits another month. The work was done in this period. The cash does not follow. That gap is where most of the cash pressure in Thai subcontract work actually lives.
Closing it is not a question of working faster. It is a question of getting the inspection date confirmed before the cutoff arrives.
Stage Complete Is Not the Same as Stage Accepted
Stage completion and stage acceptance are two different dates, and in a busy project they are rarely the same day.
Your team finishes the scope. The main contractor’s engineer may not be available for several days. If the engineer’s schedule runs past your billing cutoff, the invoice slips to the following period.
In most Thai subcontract arrangements, the monthly billing cutoff falls between the 20th and the 28th. An inspection on the 27th, when the cutoff is the 25th, means a stage complete on the 20th does not get billed until next month. Not because of a dispute. Not because the work was rejected. The stage simply was not on anyone’s inspection calendar in time.
Why a Chat Message or a Phone Call Does Not Fix This
Most subcontractors chase inspection dates through the site LINE group or a call to the engineer’s mobile. These are reasonable in a working relationship, but neither creates a deadline for the other party.
A main contractor’s engineer manages inspection requests across several projects at once. Your message lands in a thread carrying safety notices, delivery updates, and questions from other subcontractors. There is no mechanism in a chat message that tells the engineer when you need a decision, or what happens if it does not arrive.
A written inspection notice names a specific proposed date, describes what will be ready for inspection, and states the billing cutoff plainly. The engineer has everything needed to confirm a date, and a reason to do it this week rather than next.
How to Write an Inspection Notice That Gets a Date Confirmed
The document does not need to be long. One page covers everything that is needed.
Project and stage reference. Name the contract, the site, and the stage number or description from the BOQ. If the main contractor uses a reference code, use their numbering.
Scope ready for inspection. A plain description of what is complete: which zones, which systems, which floors. Specific enough that the engineer knows where to go and what to look at.
A proposed inspection date. Name a specific date, not a range. Give the engineer enough lead time to schedule the visit, but keep the proposed date inside your billing window.
The billing cutoff, stated as information. Write it simply: “Our billing cutoff for this period is [date]. An inspection before that date allows us to issue the stage invoice within this cycle.” Many engineers are not aware of their subcontractors’ billing calendars.
The contact for confirmation. One name, one number. The engineer should be able to confirm without hunting for the right person.
Send the notice by email or LINE and keep a copy in your project folder. If two working days pass without a reply, send one written follow-up.
When Should the Notice Go Out?
Work backwards from the date the invoice needs to be submitted.
If the billing cutoff is the 25th and preparing the invoice package after sign-off takes two working days, the inspection needs to be complete by the 22nd at the latest.
An inspection notice needs at least four to five working days of lead time for the engineer to schedule the visit. That means the notice should go out by the 17th.
The sequence: notice out by the 17th, inspection on the 21st or 22nd, invoice package ready on the 24th, invoice submitted on the 25th.
That sequence is achievable, but only if you know the 17th is coming before it is already the 20th. When billing stage pins sit on your project timeline, adding a pin one week before each billing pin, labelled “inspection notice due,” turns a deadline you might miss into a weekly review prompt.
What If the Engineer Does Not Reply After the Notice?
Send a written follow-up the next working day. Keep it short: name the original notice, restate the proposed inspection date, and restate the billing cutoff.
If a second working day passes without a reply, send a shorter message: the stage is ready, you need a confirmed date, and the current absence of a date will push the billing into the following cycle.
Document each step. If a question about the stage arises later, the chain of written notices and non-responses is the clearest evidence that any delay was not on your side.
A Worked Example
Seven-zone mechanical rough-in project. Zone B rough-in is complete on the 16th. The subcontractor’s billing cutoff is the 28th.
The inspection notice goes out on the 17th, proposing inspection for Zone B on the 22nd, and naming the billing cutoff of the 28th.
The main contractor’s engineer replies on the 18th confirming the 22nd. Inspection happens as scheduled. The acceptance form is signed that day.
The invoice package is ready on the 25th and goes in on the 27th, one day before the cutoff.
Without the notice, the engineer might first hear about Zone B at the weekly meeting on the 24th and schedule the inspection for the following week. Same stage, same completed work, billed one full cycle later.
FAQ
Does the inspection notice need to be on company letterhead?
Formal letterhead helps if a dispute arises later, but it is not required. A consistently formatted email or LINE message, with the project reference and scope clearly named, creates a usable record. What matters is that the document is written, dated, and sent through a channel you can retrieve later.
What if the engineer says the scope is not ready during the inspection?
Ask for the specific items that need correcting and a confirmed date for a re-inspection, both in writing. A corrections list with a re-inspection date is far better than a verbal rejection with no follow-up plan. Address the corrections promptly and send a new written notice for the re-inspection, referencing the original notice date.
How does tracking inspection notices connect to a project timeline?
When billing stages are pins on your project timeline, adding an inspection-notice pin one week before each billing pin takes one extra step during setup. That pin appears in your weekly review before the billing deadline, prompting you to check whether the notice has gone out and a date has been confirmed. A missed billing cycle costs a month of cash.
If you want to map out which stages are coming up for inspection over the next 30 days, a call is a practical starting point. We open one live project together and lay out the inspection dates against your billing calendar.