Monthly in Arrears Invoice

A monthly in arrears invoice, also known as a retrospective invoice or backward-dated invoice, is a type of billing document that is issued after services or products have been provided within a particular month. Unlike a traditional invoice that is issued in advance, a monthly in arrears invoice is typically generated at the end of a billing cycle, providing a summary of the charges accrued during the previous month.


A monthly in arrears invoice is commonly used in various industries, including information technology, to bill clients or customers for services rendered or products delivered. It allows companies to accurately calculate the charges based on actual usage or the quantity of goods provided within a specific period. This type of invoicing method is particularly beneficial for ongoing services or long-term projects where prepayment or advance billing may not be feasible or suitable.


  1. Accurate Billing: By using a monthly in arrears invoice, businesses can ensure that clients are billed only for the services or products they have actually received. This method allows for a more precise calculation of charges based on the actual usage during the billing period.
  2. Flexibility: Monthly in arrears invoicing provides flexibility for both the service provider and the client. It eliminates the need to make upfront payment or prepayments, allowing clients to have a better understanding of their cash flow and allocate their resources accordingly.
  3. Simplified Administration: With monthly in arrears invoicing, businesses can streamline their administrative processes by generating a single invoice at the end of each billing cycle instead of issuing multiple invoices in advance. This simplifies the billing process and reduces the administrative workload.


Monthly in arrears invoicing is commonly used in various industries, including the information technology sector. It is particularly applicable in the following scenarios:

  1. Service-based Contracts: For companies providing ongoing services, such as IT consulting, software development, or tech support, a monthly in arrears invoice allows for accurate billing based on the actual time spent or services rendered within the billing period.
  2. Subscription-based Services: In the IT industry, companies offering subscription-based services, such as software-as-a-service (SaaS) or cloud computing solutions, often opt for monthly in arrears invoicing. This allows clients to use the service during the month and then receive an invoice reflecting the exact usage.
  3. Long-term Projects: For projects that span over multiple months or even years, a monthly in arrears invoice provides a convenient way to bill the client for the work completed within each billing cycle. This method ensures that accurate charges are applied while allowing flexibility for project adjustments.


A monthly in arrears invoice is an effective billing tool used in the information technology industry and beyond. By issuing an invoice after services or products have been provided, businesses can accurately calculate charges based on actual usage or delivery. This method offers advantages such as accurate billing, flexibility, and simplified administration. Whether it is for ongoing services, subscription-based models, or long-term projects, using a monthly in arrears invoice allows for a streamlined invoicing process and enhanced financial management for both service providers and clients.

This glossary is made for freelancers and owners of small businesses. If you are looking for exact definitions you can find them in accounting textbooks.

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