Tax Invoice

Value-added tax (VAT) is a tax the seller collects from the customer on the government's behalf and then remits. That means the government has to know how much each company sold, and the buyer has to be able to recover the tax it paid, because VAT on business purchases is deducted from what that business owes.

The arrangement only works when both sets of books agree. If the seller records a transaction at $750 and the buyer records the same one at $1,500, the tax collected and the tax refunded don't line up. That used to happen often: a buyer would claim more purchases than it made and pay less tax, while the seller left the corresponding sale unreported. Beyond what the two parties said, there was no way to confirm a transaction had happened, and the mismatch only surfaced in an audit years later.

A tax invoice is the document built for that confirmation. One record carries the seller, the buyer, the date, the amount, and the tax, and both companies share its contents. Issued electronically, a copy goes straight into the tax authority's system, so what the two companies report gets machine-matched against each other. This makes the document closer to a filing submitted to the government than a notice sent to a customer.

The required fields are set by law, and a document with one of them missing or wrong is not accepted as evidence. In practice there are five groups to fill.

1. Supplier and recipient. The business registration number, company name, representative's name, address, and line of business for both sides. The registration number matters most: get it wrong and the other party cannot recover the tax, which is why it gets checked before anything else on the document.
2. The date. The date the goods or service were supplied, which determines which month's filing the transaction lands in. Dating work supplied in late December as January puts the two companies in different filing periods.
3. The taxable amount and the tax. In Korea the rate is 10 percent, so a $750 service is recorded as $750 plus $75 of tax for a total of $825. The customer pays $825 while the company's revenue is $750.
4. The line items. Enough description to identify what was sold. Unlike an invoice, which lists unit prices and quantities row by row, this often comes to a single line.
5. Whether it is a request or a receipt. Marked as a request if the money hasn't arrived and as a receipt if it has, which ties into how accounts receivable gets tracked — the amounts billed but not yet collected.

The person writing it is in finance or bookkeeping on the selling side. Issuing the month's supply in one batch at month end is normal, and once a company grows the billing system issues them automatically. Automation matters here more than it looks, because the work scales with the number of customers rather than with revenue.

Three parties read it. The first is the customer's finance team, who need it to recover the VAT they paid; if it doesn't arrive they are the ones who call. The second is the tax authority, which receives a copy on issue and uses it to match both sides' filings. The third is the company's own accounting, which checks the list of documents issued against the revenue ledger.

What sets this document apart is a statutory deadline. In Korea it has to be issued by the tenth of the month following supply, and missing that date adds a penalty of one to two percent of the amount — not a small number on a large contract.

If the recipient isn't a registered business, the document doesn't apply. Cash receipts and card statements serve the same purpose for individual customers. This is why a product sold to individuals and a product sold to companies carry very different amounts of billing work.

When the amount changes, a corrected version follows. A refund or a revised contract value calls for an amended tax invoice that records the difference in the opposite direction. Nothing gets erased; a correcting record is added instead.

"Could you issue the tax invoice by the tenth?"

Past that date a penalty applies, so it's a request to hurry.

"We got the invoice but not the tax invoice. I can't get the approval through."

The two documents do different jobs, and one alone doesn't move the customer's internal process.

"The refund went through, so I'll issue an amended tax invoice."

An already-reported amount is being reversed with a correcting record.

At Pagedeck, billing an enterprise customer sends the two documents as a pair. Once Sofia closes a contract, billing sends the invoice so the customer's contact has something to attach to an internal approval request, then issues the tax invoice for the same amount so their finance team can handle the tax. Out of order, one side or the other stalls.

Last month one digit of a customer's business registration number was copied down wrong and the tax invoice had to be reissued. The customer's finance team found it while claiming the deduction and told them, and from that day the number written on the contract gets checked by two people as it goes into the billing system.

The most common mistake is treating it as the same document as an invoice. Both are pieces of paper with an amount on them arriving at the customer, so the confusion is easy. But the recipient and the purpose differ. An invoice asks a customer for money; a tax invoice reports to the government that a transaction occurred. Send the invoice and forget the tax invoice and the money arrives while the next filing catches the gap. Issue only the tax invoice and the customer's contact has nothing to attach to an approval request, so payment stops.

The other belief is that the issue date is the date revenue is recognized. The same amount appears on both, which makes the connection look natural. But revenue follows accrual accounting and gets spread across the period of delivery. Bill a year up front on a single tax invoice and that document carries a year's amount while revenue goes on the books across twelve months. Use the list of documents issued as a revenue ledger and the first month inflates while the rest look empty. The two numbers are tracked separately and reconciled by period, and a gap between them usually points at a contract billed on a schedule the revenue schedule doesn't match.