Invoice number already exists? Reuse the number of a voided invoice: a guide for Xero users

If Xero won't take an invoice number because it is already in use, a voided invoice may be holding it: Xero says you can't reuse the number of a voided invoice, while the number of a deleted draft can be reused. The only way to keep a number free is to change it before you void the invoice. This guide covers how to find what holds the number, the order of steps that keeps it free, and how to do it for a whole selection.

Checked against Xero Central on 12 October 2026 (the numbering and delete-or-void invoice pages again on 24 October) and Xero Product Ideas on 24 October 2026.

What the help pages say about numbers

Xero's page on changing numbering sets out the rules:

• A specific prefix and number combination can only be used once for a transaction type. Adding a character, so that INV-0001 becomes INV-0001a, makes it a different reference.
• You can reuse a number if you delete an invoice, credit note or quote. If you void a transaction, you can't reuse the number.
• Invoices and credit notes share one sequence, with the prefix changing between INV and CN.

Xero's page on deleting or voiding an invoice gives the practical consequence. The number of a deleted draft or awaiting approval invoice can be reused. To reuse the number of an approved invoice, you need to change the number before you void it.

Find the document that holds the number

Xero says deleted and voided invoices stay visible: on the All tab of the Invoices screen, tick Include Deleted & Voided when you search. The status tells you the fix. Deleting a draft or awaiting approval invoice frees its number. An awaiting payment invoice can be edited, so its number can be changed. A voided invoice keeps the number for good: use a different number, for instance by adding a character, which Xero treats as a separate reference. Xero's request to reuse voided numbers (171 votes) has the status Submitted.

The native way: rename first, then void

1. Clear what blocks a void. A paid invoice has to have its payment removed before it can be voided (Delete an invoice or bill payment).
2. Change the number. Open the invoice, click the menu icon, select Edit and change the invoice number, for example by adding -V. Xero's page on editing an invoice says an awaiting payment invoice can be edited in any field.
3. Void it. Menu icon, Void, then confirm.
4. Create the replacement. Xero's article on creating an invoice describes copying an existing one: select the invoice on its status tab, or open it and choose Copy to draft invoice. You can't copy from the list of all invoices.
5. Type the original number into the copy and save it.

Two details matter. If you copy several invoices at once, Xero creates one draft invoice holding all their line items, not one copy each. And if you void first and think about the number afterwards, it is too late: the number stays with the voided invoice.

Where the native way runs out

• One invoice at a time. Xero says awaiting payment invoices can't be voided in bulk, and each rename is an edit of its own. For 80 invoices, that is 80 renames, 80 voids and 80 copies.
• The order is easy to get wrong. Void before renaming and the number is gone for good.
• Voids are permanent. Xero says voided invoices can't be reinstated or restored.
• Lock dates. After a lock date is set, users can't add or edit transactions dated on or before it (Set up or remove lock dates). An invoice dated inside the locked period can't be edited, so it can't be renamed either.
• No link between old and new. The voided original and the replacement are two unrelated documents unless you write notes on both.

The faster way: Unapprove

Unapprove is a web app that works with Xero. Its unapprove run does the rename, void and copy for a whole selection of approved invoices and bills, in an order that never leaves you without a copy.

How it handles the number

• The draft copy is created first, with a temporary number made of the original number, -D and a short identifier, because Xero will not accept two sales invoices with the same number.
• The original is then renamed with -V added, or -V2, -V3 and so on if that is taken.
• The original is voided, and only then is the copy renamed to the original number. Each step is read back from Xero before the next one runs.
• Both documents get a history note naming the other, with the old number.
• For bills, the copy carries the original number from the start and no rename is needed.

It is a choice. "Keep the original invoice number on the draft copy" is a checkbox on the selection screen, ticked unless you clear it. Without it the copy gets a new number from your sequence.

What the void-only run does: nothing to the number. It voids the invoice as it is, so a voided number stays used, exactly as Xero's rule says.

What it skips, and tells you why: documents with a payment applied or a credit note allocated (why), documents inside a locked period (why) and documents for an archived contact (why). For US organisations Unapprove only voids; it does not make copies, because a copy made through Xero's API can lose automatic sales tax.

What access it asks for: your name and email to sign you in, read and write on invoices and bills, read and write on attachments, and read-only on organisation settings and contacts.

Price: free for 14 days, with unlimited previews and three documents processed in total. After that, $29 per month per connected organisation, or a one-off $49 Clean-up Pass for 7 days and up to 500 documents. Prices are in US dollars and exclude VAT and sales tax (added at checkout); the pricing page has the details.

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Related reading: the full routine in the guide to bulk unapproving invoices and bills, and what to do after a bad import, when the numbers matter most.

Questions

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