# Prevent using same sequence on earlier customer invoice: which date to use?
**URL:** https://discuss.tryton.org/t/prevent-using-same-sequence-on-earlier-customer-invoice-which-date-to-use/4840
**Category:** Developer
**Tags:** accounting
**Created:** [December 9, 2021, 4:44pm UTC](https://discuss.tryton.org/t/prevent-using-same-sequence-on-earlier-customer-invoice-which-date-to-use/4840 "2021-12-09T16:44:20Z")
**Posts on this page:** 9
**Page:** 3
### Author:  [@ced](https://discuss.tryton.org/u/ced)
#### Post date: [January 18, 2022, 9:02am UTC](https://discuss.tryton.org/t/prevent-using-same-sequence-on-earlier-customer-invoice-which-date-to-use/4840/41 "2022-01-18T09:02:18Z")
All your links state the opposite of your statement. They all say that the invoice numbering must be consecutive. And for me it is clear that consecutive means consecutive in time otherwise it means nothing. And time is recorded by the accounting date.
> [@yangoon](#):
>
> there is **no combined constraint on date and numbers for the invoice number**.
Even if this were true (which I do not understand from your links), it does not prevent to use Tryton at all.
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### Author:  [@yangoon](https://discuss.tryton.org/u/yangoon)
#### Post date: [January 18, 2022, 9:59am UTC](https://discuss.tryton.org/t/prevent-using-same-sequence-on-earlier-customer-invoice-which-date-to-use/4840/42 "2022-01-18T09:59:55Z")
> [@ced](#):
>
> All your links state the opposite of your statement. They all say that the invoice numbering must be consecutive. And for me it is clear that consecutive means consecutive in time otherwise it means nothing. And time is recorded by the accounting date.
The links state that basing on German law an invoice sequence must provide **unique** numbers. And being consecutive is the primary property of a sequence otherwise is is a random series. That doesn’t mean at all that a sequence must be coupled to a date or something else.
> [@ced](#):
>
> Even if this were true (which I do not understand from your links), it does not prevent to use Tryton at all.
I think there is enough evidence that it is true. Of course the current constraint does not prevent to use Tryton at all. We are talking about “Prevent using same sequence on earlier customer invoice” which is allowed in Germany.
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### Author:  [@sergyo](https://discuss.tryton.org/u/sergyo)
#### Post date: [January 18, 2022, 10:00am UTC](https://discuss.tryton.org/t/prevent-using-same-sequence-on-earlier-customer-invoice-which-date-to-use/4840/43 "2022-01-18T10:00:13Z")
> [@ced](#):
>
> And for me it is clear that consecutive means consecutive in time otherwise it means nothing. And time is recorded by the accounting date
Indeed in Spanish documentation “time” for customer invoices is issued time; and it is recorded by invoice date.
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### Author:  [@ced](https://discuss.tryton.org/u/ced)
#### Post date: [January 18, 2022, 10:09am UTC](https://discuss.tryton.org/t/prevent-using-same-sequence-on-earlier-customer-invoice-which-date-to-use/4840/44 "2022-01-18T10:09:26Z")
> [@yangoon](#):
>
> That doesn’t mean at all that a sequence must be coupled to a date or something else.
It means that otherwise if you can not order invoices, you can not have consecutive property.
> [@yangoon](#):
>
> We are talking about “Prevent using same sequence on earlier customer invoice” which is allowed in Germany.
And which is allowed in Tryton but enforcing consecutive property.
> [@sergyo](#):
>
> Indeed in Spanish documentation “time” for customer invoices is issued time; and it is recorded by invoice date.
Well it is a little bit more complex because it is a combination of invoice and accounting date and the period of the sequence.
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### Author:  [@timitos](https://discuss.tryton.org/u/timitos)
#### Post date: [January 19, 2022, 7:36pm UTC](https://discuss.tryton.org/t/prevent-using-same-sequence-on-earlier-customer-invoice-which-date-to-use/4840/45 "2022-01-19T19:36:39Z")
While I agree with @yangoon that there is no combined constraint on date and numbers of the invoice number I consider the issuing of invoices with a date in the past as bad practice. Especially since the date of delivery/service needs to be part of the invoice. Even if the business transaction to which an invoice relates is in the past the invoice date should be not older than today. I think the proposed changes will allow Tryton to be used in Germany for issuing invoices without any problems.
For the record, this is the only place where the requirements for an invoice number in germany are written down in german law (Section 14.5 Paragraph 10):
> **[Umsatzsteuer-Anwendungserlass – konsolidierte Fassung (Stand 8. August 2025)...](https://www.bundesfinanzministerium.de/Content/DE/Downloads/BMF_Schreiben/Steuerarten/Umsatzsteuer/Umsatzsteuer-Anwendungserlass/Umsatzsteuer-Anwendungserlass-aktuell.html)**
>
> Auf Grund der Allgemeinen Verwaltungsvorschrift zur Aufhebung der Allgemeinen Verwaltungsvorschrift zur Ausführung des Umsatzsteuergesetzes (Umsatzsteuer-Richtlinien 2008 - UStR 2008) vom 6. Oktober 2010 (Bundesanzeiger Nr. 165 vom 29. Oktober 2010,...
There are no requirements other than those described there.
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### Author:  [@edbo](https://discuss.tryton.org/u/edbo)
#### Post date: [January 20, 2022, 10:02am UTC](https://discuss.tryton.org/t/prevent-using-same-sequence-on-earlier-customer-invoice-which-date-to-use/4840/46 "2022-01-20T10:02:10Z")
In The Netherlands the same applies as for Germany. Just a sequence of consecutive numbers. It is possible to have multiple sequences but there should be a good reason for that.
> **[Aan welke eisen moeten facturen voldoen voor uw btw-administratie? |...](https://www.belastingdienst.nl/wps/wcm/connect/bldcontentnl/belastingdienst/zakelijk/btw/administratie_bijhouden/facturen_maken/factuureisen/)**
>
> Uw factuur moet aan een aantal eisen voldoen. Zo moet u enkele basisgegevens vermelden. In sommige situaties zet u meer of juist minder gegevens op uw factuur.
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### Author:  [@sergyo](https://discuss.tryton.org/u/sergyo)
#### Post date: [January 22, 2022, 1:40pm UTC](https://discuss.tryton.org/t/prevent-using-same-sequence-on-earlier-customer-invoice-which-date-to-use/4840/47 "2022-01-22T13:40:34Z")
I totally agree that invoice date in customer invoices should be preferably today and date in past should be avoided. This is not applicable to accounting date which should be the date when the goods are delivered or services are provided.
So for this reason I don’t see why invoice number must use accounting date to create consecutive numbering in time. Because imho it is not achieved in the moment I post invoices with accounting date in the past.
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### Author:  [@sergyo](https://discuss.tryton.org/u/sergyo)
#### Post date: [February 21, 2022, 4:35pm UTC](https://discuss.tryton.org/t/prevent-using-same-sequence-on-earlier-customer-invoice-which-date-to-use/4840/48 "2022-02-21T16:35:30Z")
> [@sergyo](#):
>
> > [@sergyo](#):
> >
> > Anyway we have just queried to “agencia tributaria” about it.
>
> FYI my mistake I thought @roliver sent an email to “agencia tributaria” but seems there isn’t this contact mechanism. So we have to phone.
Finally we have [official answer](http://cloud.looseapps.com/files/Contestaci%C3%B3n%20%20fecha%20factura%20000846-22.pdf) about what date to use in customer invoice numbering (note that first two pages were removed because they contained sensitive information).
As I said along thread, in Spain the date to use for getting a consecutive numbering in customer invoices is “invoice date”.
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### Author:  [@david\_auto](https://discuss.tryton.org/u/david_auto)
#### Post date: [February 24, 2022, 4:08pm UTC](https://discuss.tryton.org/t/prevent-using-same-sequence-on-earlier-customer-invoice-which-date-to-use/4840/49 "2022-02-24T16:08:47Z")
una recomendacion borra el csv del documento porque se puede acceder a los datos privados.
un saludo
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