Using customer-specific invoice prefixes

By default, every invoice you send draws from one account-wide numbering sequence — INV-1001, INV-1002, INV-1003, and so on. Customer-specific invoice prefixes let you give an individual customer their own prefix and their own independent numbering sequence instead.

For example:

• Acme Corp → ACME-001, ACME-002, ACME-003
• XYZ Logistics → XYZ-001, XYZ-002
• Every other customer → your normal account-wide sequence, unaffected

When to use a customer prefix

Set one up when:

• you want a customer’s invoices grouped or identified by their own prefix
• a customer requires a specific invoice numbering format
• you want a customer’s numbering kept completely separate from your general invoice sequence

If none of that applies, you don’t need to do anything — customers without a configured prefix always continue on your normal account-wide sequence, even after you turn this feature on for other customers.

Turn on customer-specific prefixes

1. Go to Settings → Invoices.
2. Turn on Use a customer prefix.

Turning this on doesn’t change anything by itself. It only makes the per-customer prefix fields active — no customer gets their own sequence until you set a prefix for them individually.

Set a prefix for a customer

1. Go to Clients and open the customer.
2. Select Edit.
3. Under Invoice Numbering, enter an Invoice prefix.
4. Optionally, enter a Starting invoice number.
5. Save.

Prefixes are 1–20 characters: letters, numbers, and hyphens, starting with a letter or a number. You can type your prefix in lowercase — SimplePayment converts it to uppercase automatically.

If you set a Starting invoice number, that exact number is used on the customer’s first invoice (for example, a starting number of 100 produces ACME-100 as the first invoice, then ACME-101 next). Leave it blank to start at 1.

How independent numbering works

Once a customer has a prefix, their invoices count up on their own sequence — separate from every other customer and from your account-wide sequence. Creating an invoice for one customer never advances another customer’s numbering, and never advances the account-wide sequence either.

Customers without a configured prefix — even with the feature turned on — keep using the account-wide sequence exactly as before.

Prefix rules

• Each customer’s prefix must be unique across your account — two customers can’t share a prefix.
• A customer’s prefix can’t match your account-wide invoice prefix (INV by default, or whatever you’ve set under Settings → Invoices).
• Once a customer’s sequence has started, new invoices for that customer increment automatically — you don’t need to enter a number each time.

Turning the feature off

If you turn off Use a customer prefix under Settings → Invoices, every new invoice goes back to the account-wide numbering sequence, regardless of what any customer has configured.

Each customer’s prefix and starting number stay saved — they’re just not used while the feature is off. Turn it back on and customers pick up their sequence where they left off.

What happens to existing invoices

Existing invoice numbers never change. Customer-specific numbering only applies to invoices you create after you’ve configured a prefix — invoices already sent keep the numbers they were given.

Example

Account-wide sequence:

INV-1001
INV-1002

Acme Corp (prefix ACME):

ACME-001
ACME-002

XYZ Logistics (prefix XYZ):

XYZ-001
XYZ-002

Each sequence moves forward on its own — nothing here affects the others.