Use Adjust when an issued VAT invoice is still valid, but some line items need correcting — quantity, price, VAT, description, unit, or buyer details.
The original invoice stays in place. Invoi creates a new adjustment invoice that references it. Only the differences are submitted to the tax authority (GDT), aligned with Decree 254/2026/NĐ-CP.
To replace the whole invoice instead, see Replace Invoice.
#When you can adjust
Open an issued invoice (validated or sent). In the More menu, choose Adjust.
Adjust is available only on the latest invoice in a chain:
- The invoice has not already been adjusted or replaced.
- You cannot adjust an invoice that was itself created as a replacement.
If you already issued an adjustment, open that adjustment and adjust again. Invoi stacks the changes so the form starts from the current totals, not the original F0.
#Steps
- Open the invoice → More → Adjust.
- Choose an adjustment reason (required): incorrect quantity, unit price, VAT rate, description, unit of measure, buyer information, or a custom reason.
- Edit line items as if you were creating a new invoice:
- Change quantity, price, VAT, description, or unit. - Add a new line. - Mark a line deleted.
- Review the PDF preview. Unchanged lines are omitted; deletions appear as negative lines, additions as positive, and edits as a minus of the old line plus a plus of the new one.
- Sign and issue. Invoi writes the legal header note automatically, for example: *Điều chỉnh cho hóa đơn [series], [number], [date], lý do [reason]*, and files 04/SS-HĐĐT with GDT.
#What gets submitted
The adjustment invoice carries deltas only:
- Subtotal Δ, VAT Δ, and total-to-pay Δ are shown on the form.
- F0 (original) + F1 (this adjustment) equals the corrected totals.
- The new invoice is labeled as an adjustment of the source invoice, with a link back.
- The tax-authority notification is submitted with the adjustment — you do not file 04/SS-HĐĐT separately.
You can keep adjusting the latest invoice if further corrections are needed.