Invoice Numbering Scheme

Where to Configure#

Go to Admin → Settings → Billing → Invoice Settings.

The numbering scheme applies to all invoices system-wide. Changes take effect on the next invoice created — existing invoices keep their original numbers.

Scheme Format#

Invoice numbers are assembled from three parts:

{prefix}{year}-{sequence}

Example: INV-2026-00042

If yearly reset is disabled, the year segment is omitted:

INV-00042

Configuration Fields#

Invoice Prefix#

A short text string prepended to every invoice number. Common choices:

The prefix is free text — use letters, numbers, and hyphens. Avoid characters that break filenames (e.g. /, \, ?) since the number is used in PDF filenames.

Yearly Reset#

When enabled, the sequence counter resets to 1 on January 1st of each year. This produces predictable per-year numbering and is required in some jurisdictions for accounting.

[!IMPORTANT] The reset is triggered by the first invoice created after midnight on January 1st. If no invoices are created on that day, the reset happens on the first invoice of the new year whenever that occurs.

When disabled, the sequence is a single ever-increasing number across all years.

Zero-Padding Width#

Controls how many digits the sequence is padded to. A width of 5 means:

A width of 0 disables padding entirely: sequence 42 is shown as 42.

Starting Number#

You can set the starting sequence number once, before any invoices exist. This is useful when migrating from another system and you want the new sequence to continue from where the old one left off.

[!WARNING] Do not change the starting number after invoices have been created. The sequence is driven by a database counter — manually adjusting it can cause duplicate invoice numbers, which breaks accounting records. If you must change it, update the sequence in the database directly and verify no conflicts exist.

How the Sequence Works#

The sequence uses a database-level atomic counter (auto-increment). This means:

• Numbers are never reused, even if an invoice is cancelled
• There are no gaps filled — a cancelled invoice leaves a gap in the sequence, which is normal and expected
• Concurrent invoice creation is safe — two invoices created simultaneously will always receive different numbers

[!TIP] Gaps in invoice numbers caused by cancelled invoices are normal. Auditors understand this. What matters is that numbers are unique and sequential — not that there are zero gaps.

Changing the Prefix#

You can change the prefix at any time. The change applies to the next invoice only. Existing invoices retain their original number. If you rebrand (e.g. from INV- to ACME-), old invoices will still show the old prefix.

Examples by Configuration#

Related Topics#

• Invoices Overview
• Invoice PDF