What is an Invoice? and
How Does It Work?

Understand what an invoice is, its key purpose, and how it helps businesses manage payments efficiently.

Invoicing is a fundamental part of any business transaction. Whether you are a freelancer, small business owner, or large company, invoices help you get paid, maintain financial records, and stay legally compliant. In this blog, we’ll explore what an invoice is, and how it works step by step.

What Is an Invoice?

An invoice is a formal document sent by a seller to a buyer requesting payment for goods or services provided. It serves as an official record of a transaction and outlines details such as what was sold, how much it costs, and when payment is due.

In simple terms, an invoice is a bill that tells your customer:

  • What they are paying for
  • How much they owe
  • How and when to pay

Invoices are used in both business-to-business (B2B) and business-to-customer (B2C) transactions.

Invoices in B2B and B2C Transactions

Invoices are commonly used in both business-to-business (B2B) and business-to-customer (B2C) transactions, but the way they are used can differ slightly depending on the type of sale.

1. Business-to-Business (B2B) Invoices

In a B2B transaction, one business sells products or services to another business. Invoices are essential in these transactions because payments are often made after delivery and may follow agreed payment terms such as Net 30 or Net 60.

Example: A digital marketing agency provides services to a corporate client. After completing the work, the agency sends an invoice detailing the services, costs, tax information, and payment deadline.

2. Business-to-Customer (B2C) Invoices

In a B2C transaction, a business sells directly to an individual customer. Invoices in B2C are often simpler and may be issued at the point of sale or immediately after a purchase.

Example: An electronics store sells a laptop to a customer and provides an invoice showing the product price, tax, and total amount paid.

How Does an Invoice Work? (Step-by-Step)

Step 01

Goods or Services Are Delivered

Step 02

Invoice Is Created

Step 03

Invoice Is Sent to the Customer

Step 04

Customer Reviews the Invoice

Step 05

Payment Is Made

Step 06

Invoice Is Recorded as Paid

Step 01: Goods or Services Are Delivered

The invoicing process begins when the seller delivers the agreed goods or services to the customer. This may involve shipping physical products, completing a project, or providing professional services.

Why this step matters:

  • Confirms that the seller has fulfilled their obligation
  • Establishes the basis for billing
  • Ensures the customer receives value before payment (in most cases)
  • In some situations, such as advance payments, an invoice may be issued before delivery

Step 02: Invoice Is Created

After delivery, the seller prepares an invoice containing all essential details, including invoice number, seller and buyer information, item descriptions, prices, taxes, and payment terms.

Why this step matters:

  • Provides a clear and official request for payment
  • Ensures transparency in pricing
  • Helps avoid errors and disputes
  • Invoices can be created manually or using invoicing or accounting software

Step 03: Invoice Is Sent to the Customer

Once created, the invoice is sent to the customer through an appropriate channel such as email, invoicing software, or printed copy.

Why this step matters:

  • Officially notifies the customer of the payment request
  • Starts the payment timeline
  • Creates a communication record between buyer and seller
  • Digital invoices are faster and easier to track than paper invoices

Step 04: Customer Reviews the Invoice

The customer reviews the invoice to verify the accuracy of the information, including item descriptions, quantities, prices, taxes, and due date.

Why this step matters:

  • Ensures charges match the agreed terms
  • Allows quick correction of errors
  • Prevents future disputes or delayed payments
  • If discrepancies are found, the customer may request a revised invoice

Step 05: Payment Is Made

After reviewing and approving the invoice, the customer makes payment using the agreed method, such as bank transfer, credit card, cash, cheque, or online payment gateway.

Why this step matters:

  • Completes the financial transaction
  • Helps maintain healthy cash flow for the seller
  • Fulfills the buyer’s payment obligation
  • Timely payment strengthens trust and business relationships

Step 06: Invoice Is Recorded as Paid

Once payment is received, the seller updates the invoice status to “paid” in their accounting records. A payment receipt may also be issued to the customer.

Why this step matters:

  • Keeps financial records accurate
  • Helps track revenue and outstanding invoices
  • Supports accounting, audits, and tax reporting
  • This step officially closes the transaction

Key Elements of an Invoice

The invoice number is a unique identification code assigned to each invoice. It helps businesses track payments, manage records, and reference specific transactions easily.

Why this is important:

  • Prevents confusion between multiple invoices
  • Helps in accounting, audits, and tax reporting
  • Makes it easier to follow up on unpaid invoices

Frequently Asked Questions


When should an invoice be issued?+
What is the purpose of an invoice?+
Can an invoice be used as proof of payment?+