The financial authorities usually require an uninterrupted sequence of invoice numbers to ensure there are no missing or duplicated invoices, which could indicate errors or manipulation of the invoice records.

To comply with this requirement, PortaBilling generates invoices using an uninterrupted invoice number sequence across the entire environment. Additionally, you have the option to enable individual uninterrupted sequences for your resellers (since they usually act as an independent company) or specific customers (this is used mainly for large enterprise customers to satisfy the requirements of their procurement department). Let's explore these options in more detail.

By default, any invoice number sequence starts from “1,” e.g., the invoices within an environment will be generated with numbers 1, 2, 3, and so on. In case of using multiple sequences in parallel, it is highly recommended to start each sequence with a distinct prefix, e.g., invoice numbers for all retail customers would start with 888 (e.g., 888000001, 888000002, etc.), while invoice numbers for all enterprise customers would start with 999. This practice ensures easy differentiation and clear identification of invoices. Contact the PortaOne’s support team if you wish to start a sequence with a specific prefix.

How to configure the invoice number sequence

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PortaBilling allows you to set individual invoice number sequences for:

The general configuration of the invoice number sequence is set on the “Company info” page.

The general configuration of the invoice number sequence

The general setting can be overridden for a specific customer, reseller, reseller’s customer, or distributor.

The general setting can be overridden for a specific customer, reseller, reseller’s customer, or distributor

Individual for environment

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This option means that in a given environment, sequential invoice numbering is consistent across all entities, including direct customers, distributors, resellers, and the customers of resellers.


Suppose a service provider called “Owl Telecom” offers services for retail customers, and also engages resellers to increase sales. “Owl Telecom” uses a single invoice number sequence within their system, so that the customer John Doe receives invoice #888001, followed by customer Adam Smith with invoice #888002, reseller ABC with invoice #888003, reseller XYZ with invoice #888004, and so on.

Individual for reseller

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In order for resellers to comply with the requirements of financial authorities and have an uninterrupted sequence of customer invoices, it’s recommended to use this option. This enables each reseller to have their own individual invoice number sequence.


A direct customer of “Owl Telecom” receives invoice #888001, a distributor receives invoice #888002, and a reseller receives invoice #888003. At the same time, the reseller’s customer A receives an invoice number #555001, followed by customer B with an invoice number #555002, and so on.

Individual for customer

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Sometimes large enterprise customers may require their own invoice sequence to meet the requirements of their financial department. The “Individual for customer” option is typically set on the customer level, so that only a specific customer has an individual sequence.


"Owl Telecom'' enables an individual invoice number sequence for their large customer called “ABC enterprise.” As a result, “ABC enterprise” receives invoice #777001 followed by invoice #777002, #777003, and so on. All other customers share a common sequence: customer A receives invoice #888001, customer B receives invoice #888002, and so on.

When you set the individual invoice number sequence for a customer who already has existing invoices, the new numbering will continue starting from the last invoice number generated. This adjustment will not impact the consistency of the number sequence for other invoices across the environment.


Let's say that under the sequential numbering per environment, "ABC Company's" invoices are numbered 888096, 888207, and 888212. After changing the sequential numbering to “Individual for customer,” "ABC Company's" next invoice will be numbered 888213, with their subsequent invoices continuing sequentially (888214, 888215, etc.).

If you set the “Individual for customer” sequence option on the environment level (on the Company info > Invoicing and taxation panel), an individual invoice number sequence will be used for each entity within the environment, including direct customers, distributors, resellers, or resellers’ customers.

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