It’s no secret that a properly filled-out invoice will help you better track your company’s financial performance, assist with tax prep, and give you insight into how well specific marketing strategies are working for you. Accuracy while creating your first invoice is crucial to properly document income; one misplaced letter or number can have big implications later on.

An invoice number is one such metric for an individual invoice, and it is an important detail to be added to an invoice. Getting this number right assigned to each invoice is of key importance for small business owners. This blog will go through the most fundamental invoice reference and details.

Let’s start with a clarification and process to generate an invoice number.

What is an Invoice Number?

An invoice number is an identification number connected to a specific invoice. It lets any business owner keep tabs on multiple invoices you’ve ever issued to a client.

Most frequently, it takes the shape of a custom invoice number series of letters, characters, letters, or all combined. The importance of this number in an invoice is that it helps in identifying the invoices and making sure that they are not duplicated.

The invoice numbers aren’t just randomly assigned sequentially; there’s a logic behind every digit in each next invoice number sequence. Understanding why each piece of information is included on the invoice and why they are in that particular order will help a business owner create invoices that are more organized documents going forward.

This simple yet crucial data is a crucial part to generate an invoice number and the invoicing process and hence, let’s take a look at its importance.

Importance of Invoice Number


An invoice number is a unique identifier or unique number, that must be assigned to every invoice created. It was crucial even in the days of paper invoices. It is also the first time a client learns that an invoice has been delivered. If the document lacks an invoice number, your customer will be unable to locate it.

So let’s begin with the importance of invoice no. on the invoice.

Document your Income for Tax and Accounting Purposes

It takes a lot of effort to keep track of all the different projects and multiple clients throughout the year to know how many clients you billed and how much money you made. Because invoice numbers are consecutive, you can see how many future invoices you sent out throughout a certain period. It is crucial for your accountant and the duration of tax season. It will be simple to anticipate your revenue and keep track of incoming payments since you will be able to describe exactly how many jobs you completed and how much you get paid.

Organize your Invoices

It may be easier to discover invoices with invoice numbers when you need them. For example, you could need to respond to a client inquiry, confirm payment status, or refer them to your accountant. Invoice numbers, regardless of the nature of the work, the identity of the same client, or the cost of the project, give a handy way to look up and identify individual invoices. You can simply locate the information you need in your records by the unique identifier or record number assigned to each of your bills.

Keep Track of your Credits and Payments

Invoice numbers are one of the most efficient methods for payment processing and payment tracking purposes and commitments made and still to be made. In the absence of invoice numbers, regardless of your payment terms, you’ll have to track payments using work information or customer contact information, neither of which is required for each transaction. They also guarantee that you are not repeatedly requesting payments from clients, which may be confusing and difficult to reverse.

Improve your Company’s Professionalism

Customers will consider your service organization more credible and competent if it is more organized and mobile. Clients will know you mean business if you send out professional invoices with a unique record number assigned, business logo, project details, contact information, and price.

“Before Moon Invoice, managing our invoices and estimates appeared overwhelming. Thanks to Moon Invoice for making it a breeze and reducing administrative tasks by 50%. If I ever do have questions, customer support is very quick to respond. I can create invoices and estimates with free invoice templates for the maintenance services provided during installations, invoice my clients after projects, and keep tabs on our finances, all in one place.”

Split Equipment Installation Service Company

How to Create an Invoice Number?

You might be able to generate more well-organized bills in the future if you can explain the reasoning for each item on the invoice and the sequence in which it appears. This is also true for invoice numbers.

You may generate an adequate number for your firm by following the recommendations below:

  • The first item to consider when establishing a first invoice number is your company name. Because your company name will appear at the start of the number sequence, it must be both effective and understandable. A memorable name might help your clients remember your firm even after paying the bill.
  • The sequence is determined in the second process of establishing a new invoice number. A simple algorithm can also be employed.
  • On each invoice, make sure the invoice numbers are visible and easy to discover.
  • Maintain a digital record of every invoice you send. Both the buyer and seller need this record.
  • To maintain uniformity, choose a logical invoice number system and stick to it.

An invoice number generator software or online invoice creator is a common method for creating, saving, and automating invoices. It not only lowers your margin for error, but also accelerates and streamlines the operations of drafting, issuing, and tracking old invoices. Furthermore, the sooner you release bills, the more probable it is that you will receive full and on-time payment.

An efficient invoicing tool, such as Moon Invoice, can generate invoice numbers automatically, supporting you to avoid duplicate payments, preserving uniformity, and remaining organized.

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Best Practices When Using Invoice Numbers

Consistency is essential when constructing a number sequence based on a number pattern. Clients will find it easier to handle and track finished bills as a result. If you supply a code, make certain that it appears on the invoice so that the code and invoice number are linked.

Now, here are some best practices to help you in getting started:

  • Make sure that each number assigned is unique; it can begin with any number. Check the first invoice number to have a sequential code for the best option.
  • Invoices should be assigned in a sequential number. If you’re employing a mathematical sequence, give some opportunity for expansion. If you begin with a huge number and conclude with a smaller one, ensure that the number of digits in between is constant. If you utilize a date-based sequence, make sure you use the same year, month, and day each time.
  • Invoice numbers are to be assigned in the sequence of their creation.
  • When constructing invoice numbers, any approach is permissible, such as using simply the digits 001, 002, 003, etc., adding the customer name CN001, CN002, etc., or even adding the project name or number PN-CN-001, PN-CN-002.
  • Invoicing software can assist you with the sequential numbering method or creating a sequential number invoicing system with an invoice template.

How to Assign Invoice Numbers?

Here are some of the best methods of assigning invoice numbers for small business owners assisted with examples for better understanding.

Sequential Invoice Numbering

It is the most common effective invoice numbering system, mostly used by smaller firms or freelancers, due to its lack of complexity. If you produce your invoice numbers sequentially, each new invoice will move you up a number. You can start with 1, 2, 3, or even 0001, 0002, 0003. The most often used method for reliably numbering invoices is, to begin with, 9 zeros, followed by a 1.

Always place the clients’ names and the total amount owing on a separate sheet when time-consuming manual numbering. This information should be maintained on hand during any accounting period in case there are any inaccuracies or duplicate invoice numbers in future encounters.

When utilizing accounting software, each new transaction generates a unique invoice number. The software prevents you from entering a duplicate number.

Chronological Invoice Numbering

In this particular invoice numbering system, you indicate the manufacture date to obtain more extended, more particular invoice numbers. It uses chronological alphanumeric invoice numbers for analysis.

The following may be the first bill of the day on March 14, 2021:
Serial number: 20210314-001
Format: YYYY-MM-DD-001

The date makes up the first part of this number, and the order number, which rises by one with the previous sale, makes up the second part. To further customize the invoice, you may add the client’s number.

Customer Invoice Numbering

With a logical invoice number system based on the customer number, you may select whether or not to insert the date. Remember that the sequence number is unique after any invoice numbering system.

The customer number comes first in this arrangement, followed by the date, and then the sequence number. This allows for keeping track of the numbers and avoiding duplicates.

The following is an example of a sale for a customer with client number 4032 on October 30th, 2020:

Invoice number: 4032-001 or 4032-20201030-001

Project-based Invoice Number

The project number is your last option for referencing your invoices. For example, construction businesses are ideal candidates for employing this method since they manage several projects or have critical project figures.

The organizational structure of this logical invoice number system is divided into two parts: project number + customer number + sequence number and customer number + project number + sequence number.

The invoice number format for client number 1710 and project number BKJB702 is as follows:

Invoice number: BKJB702-1710-01
Invoice number: 1178-BKJB702-01


So, when it comes to invoicing numbers on company invoices and get paid faster, they are fully determined by the company that sends invoices.

An invoicing software like Moon Invoice not only generates invoice numbers for you but also fully automates the invoice process for your company.

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Choose the finest method or software for organizing your bills based on your needs. If you need more help with invoicing, make sure to go through the FAQs.