how to generate an invoice number

How to Generate an Invoice Number in WooCommerce

Let’s say after those hundreds of hours of brainstorming, business idea development, eCommerce store development, and marketing, you are finally getting those precious orders.

Is your job done?

Nope, your job is actually half done. So far, you have tried to impress your customer and earn their trust for them to order something from your store. You haven’t yet earned their satisfaction.

In order to turn them into loyal returning customers, there’s no alternative to earning your customers satisfaction.

But how do you earn their satisfaction?

By fulfilling the orders properly.

How well you meet your customer’s needs as an online merchant can have a direct impact on your business’s success. That’s why it’s so important to have a streamlined order fulfillment system in place to increase sales and customer satisfaction.

When a customer places an order with you, they anticipate prompt delivery of their merchandise. You’ll have more success getting customers to buy from you if you can consistently deliver what they expect.

A happy customer base is a byproduct of an effective and adaptable order fulfillment process that eliminates the need for returns, damages, and other order-related headaches. Therefore, you need to develop an efficient order fulfillment process.

One significantly important element of the order fulfillment process is creating and sending invoices right after your customers complete their checkout process with their payment details. And one essential element of any invoice is the invoice number.

In this article, we will discuss what WooCommerce invoices are, why invoice numbers are important and how to generate an invoice number in WooCommerce. Let’s dive in, then.

What is a WooCommerce invoice?

Invoices and bills are official business documents issued by a seller to a purchaser to reflect the monetary value of a transaction. In addition to their obvious financial and statutory uses, they may also be used for stocktaking purposes. Invoices, in short, are vital for maintaining an accurate accounting of your financial dealings.

In the world of e-commerce/WooCommerce, invoices are typically sent after a customer has placed an order or received a shipment. This document serves as a confirmation of the customer’s order and lists the items ordered along with their quantities and respective prices.

In addition, the invoice will act as proof of evidence in the event that the customer makes a fictitious claim regarding the transaction.

Let’s check out the essential elements of an invoice.

  • Invoice number
  • Order number
  • Company information
  • Customer’s information
  • Date
  • Payment method
  • Products purchased
  • Price and quantity
  • Tax information
  • The subtotal and Total amount charged

What is a invoice number?

An invoice’s invoice number (or invoice ID or reference number) is a special, sequential number. Having a unique identifier for each transaction helps with tracking and helps eliminate the possibility of double payments. It can consist entirely of digits or a combination of digits and letters.

When it comes to tax time and keeping track of your earnings, nothing is more crucial than having a record of your invoice numbers. They also facilitate the monitoring of payments and the handling of past-due invoices.

There needs to be a distinct invoice number for each bill that gets sent out. Invoices are not valid documents unless they contain the unique invoice number assigned to each one.

Why is the PDF invoice number different from the WooCommerce order number?

We are aware that WooCommerce is a plugin for WordPress, and when you create something on WordPress, the content management system stores that information as a record in the table called wp_posts in its MySQL database.

All your content in WooCommerce sites, such as blog entries, page additions, image uploads, attribute names, tags, and other metadata, WordPress recognizes as “posts” and provides them with their own distinct post ID. WooCommerce-related content, like products, orders, and so on, is treated as post types as well and given their own post IDs.

WordPress allocates the same post ID number to orders as order numbers. So, when you or a customer creates an order, the wp_posts table treats it as a new post type and gives it a unique ID number.

WooCommerce assigns and displays the same ID number as the order number. Therefore, order numbers are not sequential in WooCommerce.

For example, if you place two orders between the creation of a new product and the uploading of an image for that product, the order number will not be sequential. For instance, if the first order was #50, the new product would be #51, the image would be #52, and the next order would be #53.

This is not the best approach for invoices, though, as the majority of tax authorities require that the numbers on invoices be consecutive and uninterrupted. Although, you can make the order number in WooCommerce sequential with the help of the same plugin we will use to create invoice numbers.

First, let’s discuss why invoices and sequential invoice numbers are important for your WooCommerce business.

Why WooCommerce invoices and invoice number is important?

Invoices are an integral part of any professional WooCommerce business, and invoice number is an essential element of any invoice. Let’s check out some of the reasons why they are so important for your store.

Easy to find and track an order

If you get a lot of orders every day, it would be impossible to manually search through them all whenever you need information about a specific order. Therefore, it will save you a great deal of time if you give each order its own short, unique digit code.

Let’s say a customer has a concern or question about an order they placed. In that case, they can quote their invoice number, and you can look up their purchase details and respond to their concerns in a flash.

Easy to estimate total orders

When your invoice numbers are in sequential order, you can simply look at the latest invoice number to figure out the total number of orders you have received.

Keeping records

The primary purpose of a PDF invoice for WooCommerce is to act as documentation and record-keeping for the business transaction. The record database of larger companies, particularly those operating on a business-to-business (B2B) model, will always require an invoice.

You should also place a significant amount of value on the invoices that you send. If you keep a formal record of every one of your sales transactions, you will be able to stay organized and know exactly what was sold and to whom at all times.

This will allow you to make more informed business decisions. Invoices should be sent even when you run a B2C store so that all parties can easily keep track of the various transactions.

Tax filing

It is important to keep sales invoice copies for tax and accounting purposes. Having a copy of your invoices with an invoice number is a necessity when filing your GST or income tax returns. The invoices can be used to spot any tax problems for the business.

An up-to-date record of sales invoices is essential for the owner of a WooCommerce company to accurately report income and guarantee that taxes are paid. Invoice numbers make it simple for the tax agency to compare your company’s sales and expenses against your invoices.

Stock management

Woo Commerce’s invoice number is a reliable indicator of available stock, letting you keep tabs on orders and anticipate outbound shipments. The invoice number and order number sequence will be useful in determining whether or not to restock in the event of an unexpectedly high volume of orders.

If you do business with customers and want to avoid being sued for fraud, you need to make sure you have a legally binding agreement with them. When you send an invoice to a client, you’re essentially entering into a legally binding contract with them.

Customers are contractually obligated to complete the orders and transactions detailed on invoices you generate and send via email using Woo Commerce’s PDF invoicing feature. It’s an undeniable fact that you and your customers cannot ignore.

In the event of a dispute or disagreement regarding a specific order, the details of the WooCommerce invoice, along with the invoice number, can be used as proof of record to defend yourself. As a result, an invoice binds both the buyer and the seller.

Shows professionalism

A well-presented and accurate invoice is a potent instrument for leaving a favorable impression on customers. Even if you’re just a small-time WooCommerce merchant, sending out PDF invoices to customers is a sign of professionalism on your part.

WooCommerce invoices are a great way to set yourself apart from the competition and gain your customers’ trust.

Numerous businesses, including some of your WooCommerce rivals, fail to capitalize on the opportunity presented by an invoice. Customers’ receipt of invoices is a crucial part of the buying process, so you must never ignore them.

Therefore, after a customer makes a purchase from your company, you should issue them an invoice.

Getting paid

If you sell your goods or provide your services on a subscription basis, issuing invoices to your customers can save you a lot of time and energy in the long run by removing the need to pursue payment. Payments made via the WooCommerce invoice payment method necessitate the creation of invoices within WooCommerce.

The invoice details important information that the buyer will need to pay the seller, including the total value of the goods or services provided, the invoice number, the date payment is due, the accepted payment method, the seller’s contact information, and the total value of the goods or services provided.

A marketing tool

WooCommerce extensions like Challan allow you to customize invoices and billing templates with your company’s logo, links to related or upsell products, paid stamps, a personalized thank you note, and more.

Sending out branded invoices can help establish credibility with customers. The tone and design of the page should reflect the brand identity you’re trying to present to potential clients.

Creating an invoice with all the standard invoice components, such as the invoice number in WooCommerce and additional custom fields, can really impress your clients. The bottom of an invoice is a great place to advertise best-sellers or draw attention to time-sensitive deals.

Consistent experience

You are able to make your own one-of-a-kind invoice designs by utilizing WooCommerce invoicing plugins such as Challan. You can make sure that all of your invoices look the same by creating a personalized invoice template to use.

Trying to make your customer’s shopping journey in your Woo Store easier can have a significant impact on the amount of loyalty they have for your business. To use an analogy, if your team has access to an invoice template that is optimized for WooCommerce, it will be much simpler for them to locate the information they require in order to resolve any issues that may crop up.

How to create an invoice with an invoice number in WooCommerce?

WooCommerce does let you send invoices manually from order pages in the form of an email. However, they are email invoice and doesn’t contain all the information or elements of a professional invoice.

Also, that will not serve the primary purpose of invoices – record keeping and legal proof. You will need to create pdf invoices for your online store to fully enjoy the benefits of an invoice.

Unfortunately, WooCommerce doesn’t have the tools to create an invoice. However, that doesn’t limit you from creating invoices because you know WooCommerce does come with a humongous collection of third-party plugins and extensions.

That means there are plenty of plugins for creating pdf invoices in WooCommerce. One of the best among these is the Challan.

Challan pdf invoicing plugin


Challan is the most advanced and complete solution when it comes to creating pdf invoices in WooCommerce. Along with the invoices, it also allows you to create and download shipping labels, packing lists, and credit notes as well.

Challan is a freemium plugin where it’s highly popular free version is available in the WordPress repository. One thing we must mention is the pro version of Challan is extremely advanced compared to its rivals.

Most importantly, you can set invoice number in WooCommerce with the help of Challan. Along with that, Challan offers a plethora of customization and personalization options to play with.

We have already talked about how setting an invoice template can help you maintain consistency and make life easier for you. Well, with Challan, you can achieve exactly that.

Challan lets you design your custom invoice template and assign that to your WooCommerce system. Challan automatically generates invoices along with a unique invoice number and attaches them to the order confirmation email.

So, all your customers will receive your custom invoice right after they complete their orders. Additionally, you can also manually download the invoices from your order pages.

Challan also allows you to download invoices and packing lists in bulk.

You can also create custom invoices number with Challan. You can add prefixes and suffixes to your invoice number as well.

This plugin allows you to add a number of custom fields to your invoice template. In addition to that, it offers a number of pre-made background layouts for you to choose from for your invoice template.

You can also set a custom background image as well as custom-paid stamps and authorized signatures. And there’s also the option for you to further customize your invoices with CSS.

You can also add your brand elements, such as your logo, custom notes, and signature, and you even can attach static files, such as terms and services.

Overall, Challan is a premium plugin that lets you create a professional and personalized invoice along with a custom invoice number in WooCommerce.

Key features

  • Allows you to create custom invoices, packing lists, and shipping labels.
  • Automatically generates and attaches the invoices to the order confirmation email.
  • Allows you to generate invoice numbers in WooCommerce for the pdf invoices.
  • Lets you add prefixes and suffixes to your invoice numbers.
  • Supports adding your brand elements such as logo, custom notes, signature, paid stamps, etc.
  • Allows you to add custom fields in the invoice template.
  • Offers a number of pre-made invoice templates for you to choose from.
  • Enables you to further customize your invoice template with CSS.
  • Allows you to add static files along with the invoices.
  • Lets you download your documents in bulk.


Challan pro comes in the following packages-

Annual cost

Single Site – $29.00

Five Sites – $59.00

Ten Sites -$129.00

Lifetime cost

Single Site – $119.00

Five Site – $229.00

Ten Site – $457.00

How to generate an invoice number

Let’s first install the Challan plugin. Go to your WordPress admin panel and go to plugins and then click on Add new.

install challan

Type in the plugin name in the search box and install & activate the plugin.

Your job is pretty much done. Challan will generate an invoice number along with the invoice itself for all future orders and attach them to the order confirmation emails automatically.

Let’s create a demo order and checkout the invoice.

download invoice

Your customers can also download the invoice and credit notes from their My Account page or from the order complete page.

As you can see, the invoice number is 2 here. You can change the sequence as well as add prefixes and suffixes to it from Challan’s settings. Let’s check how to do that.

After you install Challan, you will find a new menu for Challan in your WordPress menu panel. Hover over and click on settings.

This is how the settings page initially looks like when you install Challan free version. You can preview all your changes in the right panel.

Scroll down to the Order settings section.

There you will find the following invoice number settings.

  • Next Invoice No.
  • Invoice No. Prefix
  • Invoice No. Suffix

From next invoice no. you can set a custom invoice number. You can set a digit, and from the next order, Challan will follow that number sequence. Let’s find that out with an example.

For instance, suppose you want to set the number 100 in the Next Invoice No. box. Put 100 in the box, and remember to save your changes.

Let’s create another demo order and check the invoice.

As you can see, the invoice number is now next to 100, which is 101. If you had put 5 in the box, the next invoice number would be 6. The default invoice number Challan will start from is 2.

Let’s see what suffixes and prefixes can do for us. Let’s say you have a special SKU code – WST, and you want to place the year in your invoices.

Here’s how the invoice number will look in your next invoice.

Now that we have checked how to create invoice number in WooCommerce with Challan free version let’s now find out what the pro version offers.

Challan pro is surprisingly advanced and changes your invoice customization game with a plethora of new options. The pro version offers a separate menu panel for invoices, packing slips, and shipping labels.

Go to the invoice tab and scroll down. You will find a separate Invoice number section now.

In the Numbering type dropdown, you will find three options.

  • Prefix + Custom Sequence + Suffix
  • Prefix + Order Number + Suffix 
  • Order Number

Let’s start with just the order number. Select that and save the changes. Create a demo order now and download the invoice.

As you can see, the invoice number is created according to the order number.

Now select the Prefix + Order Number + Suffix option from the dropdown now. You can set your own custom prefixes and suffixes or set date macros. Available date macros are –

  • {{day}}
  • {{month}}
  • {{year}}

Let’s give day as prefixes and month and year as suffixes.

Here’s how it looks in the invoice.

Now, if we choose the custom sequence option, the Next Invoice No. option will pop up.

We have already seen how it works in the free version of Challan. Let’s check an invoice now.

As you can see, by default, the invoice number is 2, along with the prefixes and suffixes.

Wrap up

A major factor in your store’s productivity is how well you handle orders and related issues. It is crucial that you equip your WooCommerce store with the means to generate sequential or custom invoice numbers in order to efficiently manage the orders placed through it.

Woo Commerce’s invoice numbers provide easy access to your purchase order information, facilitating the tracking and resolution of any issues that may arise.

Hope this article on how to generate an invoice number was of help. Let us know if you have any questions or suggestions regarding the topic.

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