e-Invoicing: the five things we ask clients to fix before go-live
10 July 2026 · 4 min read
When a client tells us their e-Invoicing project is behind, it is almost never the software. In the sessions we deliver through CWC Corporate House, the delays trace back to customer master data that was never tidy, and to a billing habit that assumed an invoice could be quietly corrected after issue. Once a document is validated and transmitted to LHDN, that habit stops working.
1. Clean the master data before anyone maps a field
Customer and supplier records need complete legal names, registration numbers, TIN details and addresses. We ask for a single cleaned master list, owned by one named person, before mapping starts. In the files we review, duplicate customer codes — the same buyer set up twice by two salespeople — are the single most common cause of rejected submissions.
2. List every document that touches revenue
Not just invoices. Credit notes, debit notes, refund notes, self-billed situations for foreign suppliers, and consolidated documents where they are permitted. For each one we ask the same three questions: who prepares it, who approves it, and exactly how a correction will be made. Teams that cannot answer the third question are the ones who struggle in month one.
3. Fix the timing, not just the format
Validation puts a deadline inside your billing routine. Clients who used to bill in a month-end batch generally have to move to continuous issuance. Set the cut-off, then make sure sales and delivery understand that late paperwork now delays a compliant invoice — it is no longer just an internal record arriving late.
4. Test with your awkward transactions, not your easy ones
Run a parallel period on genuine transactions, and deliberately include the uncomfortable ones: foreign-currency sales, deposits and advances, part-deliveries, trade discounts, and cancellations. Those are where a mapping gap surfaces. A test built only on straightforward local sales tells you very little.
5. Write the procedure down
A one-page note covering issuance, correction, storage and the responsible person. It supports your internal controls, it shortens training for new staff, and from an audit and tax perspective it is exactly the evidence that helps if a treatment is ever queried.
We deliver e-Invoicing as in-house training built around your own documents, and we will review your process before go-live if you would like a second pair of eyes.
From the file
A trading client came to us three weeks after go-live with a rejection rate above one in five. The cause was not the mapping — it was 60 duplicate customer records created over four years, several with outdated registration details. Cleaning the master list took two days; unwinding and reissuing the affected invoices took closer to three weeks of the accounts team's time. Doing the data first would have cost them a fraction of that.
Anonymised and de-identified. Shared to illustrate the point, never to identify a client.
Reviewed by Patrick Chai Chuin Wei, CA (M), FCCA — Founder & Managing Partner. Written by the audit and tax team at C.W. Chai & Partners (AF 001844). General guidance only — it is not advice on your specific position.
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