A Debtor Register with an Aging Table — Half of B2B Invoices Get Paid Late; the Businesses That Survive Know Who Owes What, Every Morning

สรุป (TL;DR)

Global B2B payment research says roughly half of invoices are paid late and bad debts average 6–8% of credit sales. How to build a debtor register and aging table that answers "who do we chase today" in ten seconds — including the parts international templates miss in Thailand: billing dates, cheque rounds, and withholding tax.

This article covers receivables-management principles for decision support. It is not accounting, tax, or legal advice for any specific case.

The problem is not "people owe us" — it is not knowing who, how much, and for how long

Every business that sells on credit knows, vaguely, that money is out there. The questions that decide whether it comes back are sharper: how much in total, which invoice has been overdue longest, and who should get the first call today.

The global numbers say this is not a symptom of bad management — it is the normal condition of selling on credit:

Atradius's B2B Payment Practices Barometer 2024 (~6,500 firms, 31 countries) finds roughly half of B2B invoices are paid late, with bad debts averaging 6–8% of credit sales.
QuickBooks' Small Business Late Payments Report 2026 finds 59% of US small businesses carry invoices more than 30 days overdue, averaging ~$17,700 per business.
In Thailand, the credit terms SMEs are given stretched to roughly 60 days on average after 2020 — up to 120 in some industries — while SME bank credit has contracted for many consecutive quarters. The bank is not bridging the gap any more; collecting faster yourself is the only lever left.

What separates the businesses that survive is not luckier customers. It is seeing earlier and chasing systematically.

The standard tool has a name: the aging schedule

An aging table splits outstanding receivables into buckets the whole financial world reads identically:

Bucket	What it means for action
Not yet due	Normal — confirm the amount and prepare billing ahead of time
1–30 days overdue	A polite reminder, now — most invoices resolve here
31–60 days	Get a specific payment date, not "soon"
61–90 days	Escalate to writing
90+ days	Real bad-debt risk — stop adding exposure, talk at management level

The theory underneath is Richards & Laughlin's Cash Conversion Cycle (1980): cash moves in a loop — buy, sell on credit, wait to collect. Every extra day in "wait to collect" (your DSO) is cash parked in your customer's account while you borrow on overdraft to cover it.

Three places international aging templates break in Thailand

English-language aging templates are everywhere. They break against Thai payment practice in three specific places:

1. Billing rounds (วางบิล/รับเช็ค) — many corporate buyers accept invoice submission only on fixed dates and count credit from that day. No billing-date column means every such invoice ages from the wrong day.

2. Withholding tax — the cash that arrives is less than the invoice face value, because corporate customers withhold (3% of the pre-VAT base for services) and issue a certificate instead. A register that waits for face value keeps fully-paid invoices open forever.

3. Transfer-fee satang — a customer pays 5 baht short because of bank fees. Closed or not? Without an explicit tolerance, ghost debts of a few satang haunt the aging table until nobody trusts it.

From register to chase screen: the order that works

A good register should not stop at displaying balances — it should finish the job and rank the chasing:

Broken rows first (missing dates, mistyped years) — these invoices are silently not aging at all, which is worse than visibly overdue.
Longest overdue, then largest amount — age erodes collectability faster than size compensates.
Due-soon at the end — a confirmation call before the due date is always cheaper than a chase call after it.

That one pre-due call — confirming the invoice arrived, the amount matches, the paperwork is complete — kills the most common excuse ("we never received the documents") before it can be used.

The tool that turns this into ten minutes a morning

The B2B Debtor Register & Collection System is an Excel file built from everything in this article, plus the parts international templates miss: due dates that can run from the billing date · expected cash net of Thai withholding tax on the pre-VAT base · invoices that close themselves within a tolerance you set · a chase-today screen that ranks the work each morning · and a 26-case live self-test sheet you can open and watch compute. One purchase includes both the Thai edition and the English (Thailand) edition, generated from identical formulas.

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Frequently Asked Questions

What is an accounts receivable aging table?

It splits everything customers owe you into buckets by how overdue each invoice is — typically not yet due, 1 to 30 days, 31 to 60, 61 to 90, and over 90 days past due. One table shows where your cash is stuck and for how long. The buckets are a global accounting convention, so your accountant and your bank read them the same way you do.

Why is an old invoice more dangerous than a large one?

Because collectability decays with age. An invoice that crosses 90 days overdue is far more likely to become bad debt, and Atradius's 2024 payment survey puts average B2B bad debt at 6 to 8 percent of credit sales. That is why a chase list should sort by days overdue first and amount second.

Should the due date run from the invoice date or the billing date?

For many Thai corporate customers, from the billing date. Large Thai buyers often accept invoice submission only on fixed days of the month — the วางบิล round — and count credit terms from that submission, not from the date you printed the invoice. A register that only knows the invoice date computes the wrong due date on every one of those invoices.

Can I chase for the full face value of the invoice?

Not always. Thai corporate customers pay net of withholding tax — for services, typically 3 percent of the pre-VAT base — and hand you a withholding certificate for the difference. The cash that actually lands is less than the face value, so a good register computes expected cash per invoice and treats it as collected at that figure, not at a face value that will never fully arrive.

How often should the register be updated?

One row the moment you issue an invoice, one cell the moment money arrives — under a minute each. Reading it is a daily habit: open it every morning, because the question it answers, who to chase today, is a daily question, not a monthly one.