Kê KhaiEnterprise tax filings
All posts

Adjust or replace an e-invoice: pick the right path, don't double-count

A wrong e-invoice can be fixed with an adjustment invoice or a replacement invoice — two paths that differ in nature, in the amount written on the invoice, and in how they hit your books. Here is the rule for choosing, the sign convention people get wrong, and why keeping both the original and the replacement doubles your revenue and tax.

  • e-invoice
  • adjustment invoice
  • replacement invoice
  • invoice errors

Issuing an e-invoice by mistake happens every week: wrong buyer tax code, wrong amount, wrong tax rate. The law gives you two ways to fix it — an adjustment invoice and a replacement invoice — and picking the wrong one (or booking both) is one of those errors that quietly throws a return off and is very hard to catch yourself.

Two paths, different in nature

Both live in Điều 19 of Decree 123/2020/NĐ-CP (amended by Decree 70/2025) — “handling invoices with errors”. The core difference:

  • An adjustment invoice records only the difference — however much the error changed, that is what you write. The original invoice stays in force; the adjustment invoice stands beside it and says “adjusting invoice Mẫu số… ký hiệu… số… ngày…”.
  • A replacement invoice re-states the entire corrected invoice and replaces the original outright. It has the same legal force and becomes the basis for declaration — the old invoice is treated as no longer in use. A replacement invoice reads “replacing invoice…”.

One line to remember: an adjustment adds or subtracts a line; a replacement rewrites the whole sheet.

Which path do you take?

There is no absolute formula for every case, but the practical rule is:

  • A wrong amount / tax rate / tax figure that can be expressed as a single difference → an adjustment is usually tidier: you only record the increase or decrease.
  • An error where the whole invoice is better re-issued clean (several fields wrong, or you want one single “fully correct” invoice to reconcile against) → replacement.
  • A wrong non-amount field (buyer name, address… while the tax code is still correct) — Điều 19 lets you simply file an error notification, with no adjustment or replacement invoice at all.

In every case: once seller and buyer have agreed, do exactly one path and state plainly on the new invoice which invoice it adjusts or replaces.

The sign convention — where people slip most

For an adjustment invoice, the sign of the number carries legal meaning:

  • Adjustment up → write a positive number.
  • Adjustment down → write a negative number.

That means a downward-adjustment invoice is a negative record in your books, offsetting what was over-recorded on the original — not a new transaction. If you book it as an ordinary positive amount, your revenue and output VAT get inflated instead of pulled back down.

Why replacement so easily doubles your figures

This is the most common trap, especially for outfits new to e-invoicing:

You issue the original invoice → book it. Then you spot the error, issue a replacement invoice → book that too. Now your books hold two invoices for the same transaction.

Because the replacement invoice carries the full amount (not the difference), keeping both doubles the revenue, the output VAT, and the CIT-taxable revenue for that transaction. The correct principle: a replacement invoice replaces the original, so your books keep one of the two. The same goes for a cancelled invoice — that is not a transaction to book, but a signal to delete the original invoice’s record.

Kê Khai catches this right at import

When you import an e-invoice XML file, Kê Khai reads the invoice’s nature — it reads the tính chất indicator (original / replacement / adjustment / cancelled) and the reference block pointing to the invoice being replaced or adjusted in the XML data. If it is not an original invoice, the app does not silently import it as a new transaction — it shows a warning with the law cited, for example on a replacement invoice:

“This is a REPLACEMENT invoice — it carries the full amount and replaces the original. If you already imported the original, adding this one too will DOUBLE the revenue/tax. Delete the original invoice’s record before adding it, or keep only one of the two.”

The warning links straight to Điều 19 of Decree 123/2020, and when the reference block is present it points at the exact original invoice to reconcile (mẫu số · ký hiệu · số · ngày). This is precisely the kind of error a product built for audit-ready returns + self-checking has to block at the door, instead of letting it quietly push a return off.

  • The two adjust / replace paths + the sign convention: Decree 123/2020/NĐ-CP, Điều 19 (handling invoices with errors; amended by Decree 70/2025) — an adjustment records the difference (up positive / down negative); a replacement re-states the whole invoice and carries the same legal force as the original.

Import your invoices right

Kê Khai stands the article of law behind every figure, and catches adjustment/replacement invoices right at import so your books don’t double up or flip a sign. You can open the Kê Khai app to start your current filing period, or read more on why every figure carries the law.

This is the English edition of a Vietnamese-first advisory. Read the original: Điều chỉnh hay thay thế hóa đơn điện tử.