Introduction

A purchase order, invoice, customer, or voucher needs a unique ID before users can track it. Manual entry makes that process slow and can lead to duplicate numbers or inconsistent formats. Dynamics 365 Finance and Operations number sequences solve this problem by creating automatic identifiers when users add new records.

You can use default sequences for a new legal entity, or create custom formats such as PO1000 or PREFIX-00001. The setup also lets you control the company, number range, starting value, and increment.

Watch the practical video tutorial: Learn how Number Sequences and Auto Numbering work in Dynamics 365 Finance & Operations with this step-by-step video guide

Why Dynamics 365 Finance and Operations number sequences matter

What an auto number means in Dynamics 365 Finance and Operations

An auto number is an identifier generated by the system during record creation. Users don’t need to type the value, which keeps document entry faster and more consistent.

A generated number can contain fixed text, separators, and sequential digits. For example, a purchase order sequence might produce PO1000, followed by PO10001 for the next order. The exact format depends on the rules set by your organization.

Which business records use number sequences

Number sequences support many records across Finance and Operations. Common examples include purchase orders, sales orders, invoices, purchase vouchers, and customer accounts.

They also support many other transaction and master-data records. Dynamics 365 Finance and Operations contains more than 1,000 tables or data models, so creating every sequence by hand would take significant time.

How sequences work with legal entities

A number sequence can apply to a particular company or legal entity. This matters when different companies use different prefixes, starting numbers, or document rules.

Before you generate or edit a sequence, confirm the active legal entity. A sequence created under the wrong company may not appear when you test a customer, order, or invoice.

Generate a foundation of automatic numbers for a new legal entity

Open Number sequences from Organizational administration

Go to Modules > Organizational administration > Number sequences. This page is the main workspace for creating, reviewing, and managing automatic numbering rules.

You can create individual sequences here, change their settings, and run the generation process. For a newly created legal entity, the Generate option provides a faster starting point.

Use Generate for initial setup

Select Generate to open the number sequence wizard. The wizard creates baseline sequences for the business entities linked to the selected legal entity.

This process avoids manual setup for every table or data model. It creates a starting configuration, though the default prefixes and formats may not match your company’s preferred naming rules.

The wizard asks for details such as the number sequence code and format. A code might identify a process as Customer number, Purchase order, or Invoice.

Review entity coverage before finishing

The wizard displays the areas and entities that will receive generated sequences. Use the search or filter option when you want to review customer-related records or another business area.

In the video example, the system displayed 31 sequences for Accounts payable and 25 for Accounts receivable. These figures can differ by application version, enabled features, and environment. Select Next, review the proposed setup, and select Finish to complete the generation.

Design formats that match business requirements

Choose a meaningful number sequence code

The number sequence code is the internal name used to identify and assign a sequence. It may be called Customer numbers or Customer auto numbers.

This code differs from the number shown on the customer or document. Use a clear naming standard so administrators can find the right sequence without opening several records.

Build the visible format

The format controls how the generated identifier appears. It can combine a constant prefix, an optional separator, and a numeric portion that increases with each new record.

For a customer account, you might use a custom prefix followed by a hyphen and five digits:

PREFIX-00001
PREFIX-00002

This pattern is easier to recognize than a default company-based value. Choose a prefix that matches your internal naming rules rather than relying on the default company code.

Set scope, range, and increment

Set the scope to Company when the sequence should apply to one legal entity. Then select the company that will use the sequence.

Define the smallest allocation, largest allocation, next value, and increment. An increment of 1 creates consecutive values. An increment of 2 can produce values that move from one number to the next while skipping every other value.

The numeric range must match the format. For a five-digit sequence, a largest allocation of 99999 supports the full five-digit range and helps prevent validation errors.

Map a custom sequence to the correct process

Save the sequence without format conflicts

Before saving, check that the numeric placeholders and allocation range agree. If the format expects five digits but the range doesn’t support that pattern, Dynamics 365 may show an error stating that the format cannot contain the specified interval.

Review the constants, separators, starting value, and increment together. Changing one field may require an adjustment to another. Confirm the design before production use because some sequence settings become restricted after records are created.

Open Accounts receivable parameters

To assign a customer account sequence, go to Modules > Accounts receivable > Setup > Accounts receivable parameters. Open the Number sequences section.

Find the reference called Customer account. This reference tells Dynamics 365 which number sequence to use when a new customer is created.

Replace the default customer sequence

The customer account reference may point to a default sequence that produces a value such as SIN-0000001. To use a custom format, remove the existing selection and choose the sequence code you created.

Save the Accounts receivable parameters. Creating a sequence alone doesn’t activate it for customers; the reference must point to that sequence first. Record the old code before replacing it so you can restore the original setup if needed.

Verify the customer account number

Create a new customer

Return to Accounts receivable > Customers and select New. The customer form should automatically populate the account number.

Check the value before entering the remaining customer details. If the custom sequence is assigned correctly, the account number should follow your chosen pattern, such as PREFIX-00001.

Compare default and custom numbering

The default behavior in the video produced SIN-0000001, based on the company code and standard setup. The desired custom behavior used a custom prefix and a five-digit numeric value.

The starting number depends on the sequence settings. When you create another customer, Dynamics 365 should assign the next value, such as PREFIX-00002.

Separate numbering from customer setup

A correct account number doesn’t guarantee that the customer record will save. The customer form may still require a customer group or other required fields.

Number generation and customer master-data setup are separate tasks. If the account number appears correctly but saving fails, review customer groups, required fields, and Accounts receivable parameters before changing the sequence.

Avoid common Dynamics 365 FO auto number problems

Resolve format and interval errors

Count the numeric positions in the format and compare them with the smallest and largest allocations. Verify that the starting value fits the format and that the increment matches the intended pattern.

Also check each constant, separator, and placeholder. A small mismatch can stop the sequence from saving, even when the prefix looks correct.

Confirm company and reference settings

Make sure the active legal entity matches the company selected in the sequence. Test record creation in that same legal entity.

Then confirm that the custom sequence appears under the correct functional reference, such as Customer account. Save the parameter changes and refresh or reopen the form if it still shows the old default number.

Conclusion

Automatic numbering in Dynamics 365 Finance and Operations keeps business records unique, readable, and consistent. The Generate wizard can create baseline sequences across many entities, while custom sequences give you control over prefixes, digit length, ranges, and increments.

For a reliable setup, confirm the legal entity, generate or create the sequence, match the format to its numeric range, and assign it to the correct module reference. Test the result by creating a record, then resolve any separate setup requirements such as customer groups. Run the process in a test environment first, document the final settings, and move the configuration to production only after the numbering pattern works as planned.