Invoice numbering: formats, next number and gaps

Set the format

1. 1

   Step 1: Go to Settings and find Numbering.

   (opens the full-size image)

   Tap the image to enlarge it

2. 2

   Step 2: Type the Format. Use {n} for the number, {n:4} to pad it to 4 digits (0042), {yyyy} or {yy} for the year and {mm} for the month of the issue date. Anything else is printed as it is.

   Examples: {n} → 42; INV-{n:4} → INV-0042; {yyyy}-{n:3} → 2026-042. The Next invoice preview shows the result.

3. 3

   Step 3: Set Next number if you're continuing a sequence from another tool.

4. 4

   Step 4: Do the same for Credit note format and Next credit note (CN-{n} by default).

5. 5

   Step 5: Click Save settings.

How numbering works

• Drafts have no number. The number is given when you issue the invoice (send it, or Issue without emailing).
• Numbers go one after another without gaps, and issue dates can't go backwards.
• Once LockedHours has issued an invoice, Next number becomes read-only: the sequence continues from the last one issued.
• Credit notes have their own series and counter.
• If you imported from Harvest, Next number was set to continue after your most recent Harvest invoice, and, if the Format was still the default {n} and you hadn't issued invoices in LockedHours, the format is copied from that invoice: 2025-0008 gives {yyyy}-{n:4} (next: 2025-0009), INV-104 gives INV-{n} (next: INV-105), 42 stays {n} (next: 43). A format you had already changed is kept. The finished import page says Invoice numbers continue from … as …. Imported invoices keep their Harvest numbers.