Invoicey

Every issuer defines a numbering scheme per document type. Invoices, proformas, advance invoices and credit notes each get their own template and their own counter — which matches Czech practice, where proformas usually run in a separate sequence from tax documents.

Templates

A template is a string with {TOKEN} placeholders, resolved at issue time.

Token	Becomes	Example
`{YYYY}`	4-digit year of the issue date	`2026`
`{YY}`	2-digit year	`26`
`{MM}`	2-digit month	`05`
`{DD}`	2-digit day	`03`
`{####}`	The counter, zero-padded to the number of `#`	`0007`
`{ISSUER}`	Issuer name, slugified, max 12 chars	`nfctron`
`{TYPE}`	Document type abbreviation	`FV`

Type abbreviations follow Czech accounting convention: FV (faktura vystavená), PF (proforma), ZF (zálohová), DOB (dobropis).

{YYYY}{####}            →  20260007     most common
F{YYYY}-{####}          →  F2026-0007
{TYPE}-{YYYY}-{####}    →  FV-2026-0007  separate stream per type
{YY}{MM}{####}          →  26050007

Avoid slashes

{YYYY}/{####} produces 2026/0007, which is valid but shows up in URLs, filenames and email subjects. Prefer a dash when these values leave Invoicey.

The counter width comes from the number of # characters, not from a separate setting. {#####} pads to five digits.

Yearly reset

resetPeriod is either yearly or never.

With yearly, the counter returns to 1 the first time you issue in a new calendar year — decided by the issue date, not by the wall clock. Issuing a backdated December invoice in January uses December's sequence, which is what you want.

With never, the counter keeps climbing.

Most Czech businesses reset yearly. Combine it with {YYYY} in the template so numbers stay unique across years.

Allocation is atomic

Numbers are allocated inside the same database transaction that issues the invoice:

Lock the issuer's numbering scheme row.
Compute the next number.
Increment the counter (resetting the year if needed).
Write the invoice with that number.
Commit.

If any later step fails — validation, totals mismatch, render error — the whole transaction rolls back and the counter does not advance. Two people issuing simultaneously cannot collide; there is also a uniqueness constraint on (issuer, number) as a second line of defence.

Previewing

The next number is always shown before you issue, so you can catch a misconfigured template before it is committed rather than after.

Numbers are never reused

Cancelling an invoice does not release its number. The invoice stays in the system as cancelled, holding its number forever.

This is deliberate. A gap in an invoice sequence is a question you have to answer during a tax inspection; a cancelled invoice sitting in the sequence answers it by itself.

Changing a scheme later

You can edit the template at any time — it is only read at issue time, so previously issued invoices keep the numbers they were given. Their numbers are part of frozen snapshots and never re-render.

Editing the counter directly is possible but risky: setting it below a value you have already issued will produce a duplicate-number error on the next issue. The one legitimate reason to touch it is aligning Invoicey with a sequence you were running in a previous tool, which the import flow does for you automatically.

Numbering