In order to seed Invoice Numbers it's important to first understand how an invoice number is made up.

Invoice Numbers (and Quote and Credit Note Numbers) are made up of 3 parts.

Lets assume an Invoice Number of : INV-SAMPLE-150.

Part 1: "INV" - this is the "Invoice Prefix" found under general settings

Part 2: "-SAMPLE-" - this is the "Document Template Prefix", which can be edited under the Document Templates section for the document template in use.

Part 3: "150" - this is the auto calculated number assigned to the Invoice.

When an Invoice is created, SimplyFi will find the next available number (Part 3) that is also using Part 1 & Part 2 of the Invoice Number and assign that to the newly created Invoice.

Now, in order to seed the Invoice Number when you first get started create a new Invoice where you will see a "+" icon next to the invoice number field. Clicking this populates the invoice number field with the next available invoice number AND makes this field manually editable, which then allows you to manually insert your own Invoice Number as required. 

Once this new invoice is saved, the next time you create an invoice, the new number will be created as (seed + 1) assuming your seed value is higher than any existing invoices using the same prefix combinations.

Some examples below of how SimplyFi will create Invoice Numbers :