Invoice numbers, VAT, languages and appearance

Numbers follow the pattern prefix, year, sequence. nokko keeps no counter. Each time you open a draft, it reads every invoice in the workspace. It finds the highest sequence for that prefix and this year, and adds one.

• Set the prefix in Settings ▸ Billing ▸ Number prefix. It is INV until you change it.
• A new calendar year starts again at 001.
• The sequence is three digits, and grows past 999 on its own.
• A number with a different prefix or shape, such as INV-2026-12a, is left out of the count.

You can overwrite the number on the draft or in the form. nokko refuses a number another invoice already has, and refuses /, : or a leading dot, because the draft's number becomes its file name. Changing the number later updates the invoice but leaves the file's name as it was.

An invoice has one VAT rate, applied to the subtotal and rounded to the cent. The default comes from Settings ▸ Billing ▸ VAT %. Change it on the draft's VAT % field, or later in the form.

When an invoice carries no VAT, the form says No VAT and no article cited until you fill in VAT note. That field is in the Invoices view, not on the draft sheet. The menu at its end holds three presets, and you can type any wording. The note prints in small type under the totals, and is saved as vat-note: in the file.

• Reverse charge (EU business customer): see Reverse charge invoice wording.
• Not a VAT payer (Lithuania): cites Article 71 of the Lithuanian VAT law.
• VAT exempt (Article 44): cites Article 44 of Directive 2006/112/EC. That article sets where a service is taxed, and it is not an exemption, so ask your accountant before you use this one.

The presets are wording only. nokko does not work out which one applies to you, so check with your accountant.

An invoice can print in English, Lietuvių, Deutsch, Français or Español, whatever language the app itself is in. Set the default in Settings ▸ Billing ▸ Language, and change it per invoice on the draft or in the form.

The language changes the title, labels, table headings, and how dates, numbers and money print. The file itself always keeps 2026-11-04 and 1234.50. In Lithuanian, the title reads PVM sąskaita faktūra whenever the VAT field has a value, including 0, and Sąskaita faktūra when it is empty.

Currency is a three-letter code such as EUR or USD, set per invoice. A draft takes the client's currency, then the one in Settings ▸ Billing. With neither, the page shows plain numbers. nokko labels the amounts and never converts them, so a rate of 75 stays 75 in any currency.

nokko has one invoice layout, and you dress it with Appearance… in the Invoices view. Each change shows on the page straight away, and applies to the preview, printing and saved PDFs alike.

These settings are your stationery: there is no separate template to pick, and no way to place a full-page letterhead behind the invoice. One style applies to the whole workspace. Every invoice with hourly lines also prints its total hours and the effective hourly rate under the total.

The style is stored in .nokko/settings.json, which sync skips. The logo file travels with the workspace, but a second Mac needs Appearance… set up again.

nokko ignores the Amount column and the totals table when it reads an invoice. It works them out again from hours times rate, so the page and PDF can never add up wrongly. If you hand-edit a total in the file, the PDF still prints the computed figure. The next change in the form rewrites the table. A flat line's sum is the exception: it is taken as typed.

Hours and rates in the file must be plain numbers such as 1.50. If a row holds 1,50, the form stops rewriting the table. It says The line table in this file is not in a shape Nokko rewrites. Click Edit Text…, press Edit and correct the number.

nokko does not lock an invoice. Sent and Paid invoices stay fully editable, and each change is one write you can undo with ⌘Z. Your accounting rules may be stricter than that, so treat a sent invoice with care.

• The form edits number, client, language, currency, VAT, VAT note, dates and lines.
• Edit Text… opens the invoice as a page. Press Edit (⌘E) to change the file itself, including From, To, Notes and Payment details. These sections are kept as you write them.
• To add notes, add a ## Notes heading after the totals. Any ## heading with text beneath it prints on the page.
• The form has no period field. To change one, edit period-start: and period-end: after Edit Text… and Edit.

If something else changes the file while you edit, nokko refuses the line edit and reloads the fresh copy. You will see that the file changed on disk.