Moving to Factuza mid-year, without repeating numbers

The short version

You bring your clients and your line items across from whatever file your current program exports, you tell Factuza which number you had reached, and you carry on invoicing from there. The history of invoices already issued does not come across — we explain why below, and why you do not need it to start.

With that, your current quarter's tax returns come out right from the first invoice you issue here, and there is not a single repeated number in your financial year.

1 · Your clients and your line items

Every invoicing program exports to CSV: Holded, Quipu, FacturaDirecta, Contasol, Sage, and of course a spreadsheet. You export the client list, upload it under Clients → Import my clients, and Factuza does three things before creating anything:

• It works out which column is which and shows you, so you can correct it. It does not matter if your file says “Razón social” and “C.I.F.” instead of our names.
• It tells you what goes in, what gets skipped and what is invalid, with the counts done. No creating half of them and then getting stuck.
• It does not duplicate. If you upload the same file twice, the second time creates nothing. Clients are compared by tax number.

And there is a boring thing worth saying that saves a headache: Spanish Excel saves CSVs separated by semicolons and in Windows-1252, not UTF-8. We have taken that into account, so “José Muñoz” arrives as “José Muñoz” and “Talleres Ruiz, S.L.” is one client and not two. If your program only exports to Excel, save it as CSV first: we do not read .xlsx.

Line items —your products or services with their price and VAT— go the same way, from Line items → Import my line items. Prices in Spanish format are understood: 1.234,56 means one thousand two hundred and thirty-four point five six.

2 · Which number you had reached

This is the part that causes the most trouble and gets talked about the least. If your last number was FA2026-0117 and your new program starts at 0001, you end up with two invoices carrying the same number in the same financial year. That is not a cosmetic detail: sequential numbering is required by article 6 of the invoicing regulations, and whoever fixes it afterwards fixes it by issuing credit notes.

When you create your series in Factuza there is a field saying “Start at number”. You put 118 and that is it. From that moment the series numbers itself.

3 · “And do you not need my last invoice's hash?”

It is the question everyone who has read anything about VeriFactu asks, and the answer is no.

Each invoice generates a record chained by SHA-256 to the previous one. But that chain belongs to each invoicing software system, not to the tax number. Your previous program has its chain; Factuza starts its own. The first record you issue here comes out marked as first record in the chain —a value the tax office's own technical specification defines for exactly this— and it is as valid as the thousandth.

It had to be this way, besides: your previous program is not going to hand you its last hash, and if continuity between systems were compulsory, changing software would be impossible. The tax office correlates by tax number, not by chain.

4 · Invoice history: second phase

The invoices you already issued with your previous program are not imported, and this is a decision, not a gap we overlooked.

Those invoices were issued by a different invoicing software system. Manufacturing a chained hash for them and inserting them into Factuza's chain would mean creating invoicing records that never existed — exactly what VeriFactu exists to prevent. And the responsible declaration for this engine is signed by OBTechnologies: we are not going to sign a system that invents records.

What will come, in a second phase, is the ability to keep them as read-only history: to look them up, to track their outstanding payments and to make the returns balance for the year you switched. Without entering the chain, without a QR code and without being filed — because they already were, or did not have to be.

In the meantime: your previous program still has your history, and the obligation to preserve those records is met there. There is no rush.

So, can I use Factuza from mid-year?

Yes, and it is the normal case. With your clients in, your line items in and your numbering continued, on Monday you issue 0118 with its hash, its QR code and its filing with the tax office. From then on:

• Your tax returns —Modelo 303, 130, 390, 347— are calculated from what you issue in Factuza. In the quarter you switch you will have to add in the previous program's figures, which you have right there.
• Your hash chain starts clean and correct from your first invoice here.
• Your numbering carries on where you left it, without repeating or skipping any.

There is no need to wait for January. And given that companies have to comply by 1 January 2027 and the self-employed by 1 July 2027, waiting is not the best idea either: reaching the deadline with the process already running smoothly is worth more than reaching it on day one.

In short

• Comes across: clients, line items and the numbering you had reached.
• Does not come across (second phase): the history of invoices already issued.
• Not needed: your last invoice's hash. The chain belongs to each system.
• You can start on any day of the year, not just 1 January.