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Changing invoicing software without breaking the sequence

It is the first thing that breaks when migrating, and it does not give a friendly warning: it gives a rejection. What the rule says, in two paragraphs, and what to ask a new provider before signing.

6 min readTicuenta
In one sentence: if you are already issuing electronic documents and you change software, the numbering has to continue where it was. Starting again at 1 is not a provider's preference: it is a rejection from the tax authority.

What the rule says, word for word

For those cases where the taxpayer is already using electronic documents under the current resolution and decides to change issuing platform, they must maintain the consecutive numbering.

Annexes and structures v4.4 · Note 3

And in case there is any doubt about what happens if it is not maintained:

It will be verified that the information in the field complies with notes 1 and 3; otherwise the document will be rejected. Compliance with the sequence in generating the consecutive numbering will also be verified.

Annexes and structures v4.4 · field “NumeroConsecutivo”

And a rejection burns the number. That document is not corrected and not resent: you issue another with the next one. If the new software started wrong, it is not an error you fix — it is a run of lost numbers.

What the sequence actually is

Not a loose running number: twenty digits in four parts, and understanding how they are assembled explains why migrations break.

DigitsWhat they areDetail
1 – 3Branch or establishment001 is head office; 002 onwards, branches
4 – 8Terminal or point of saleWith a single terminal or central server, 00001
9 – 10Document type01 invoice, 04 ticket, 03 credit note, 10 payment receipt…
11 – 20The numberStarts at 1 for each branch and terminal
Which gives the detail that breaks most migrations: there is no single sequence. There is one for each combination of branch, terminal and document type. Software that assumes “001-00001” for everything works for someone with one till, and for nobody else.

What to ask before signing

  • Can I set the starting number, per series? If the answer is “it starts at 1”, that is a no.
  • Which series do you support? Branch, terminal and type — not just invoices.
  • What happens if a number is already used? Good software detects it before transmitting, not after the rejection.

And what to take with you from the old one

  • The XMLs of everything already issued, with the tax authority's signed response. Not the PDFs — those have no tax effect.
  • The last number used in each series. This is what the new software needs on day one.
  • Your customers and products, with their CABYS codes, if the old system lets you export them.
Download your XMLs before cancelling the old service. Once the subscription ends, access often goes with it — and the five-year retention obligation stays yours.
From Ticuenta

Your numbering continues where it was

You set the last number used in each series, and issuing carries on from there. Not negotiable if you are coming from another product.

See how it works

About this article. Both quotations are from the version 4.4 annex — note 3 and the validation on the consecutive number field. The composition of the twenty digits comes from the same annex.

Verified as of 24 September 2026. Tax rules change. This is information, not tax advice.

Sources: Ministry of Finance Current legal texts (Sinalevi)

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