Business logic – what is it?

Business logic is a set of rules, calculations, and relationships that determine how an IT system processes data in accordance with the way an organization operates. It determines what should happen in a given situation: who approves an order, how a discount is calculated, when an invoice is ready for payment, and what the system does when a case’s status changes.

Business logic reflects how a company actually operates. It does not concern the application’s appearance or how data is stored, but rather the rules according to which data is processed.

How is business logic created?

In traditionally built applications, there are three distinct layers: the user interface, the data layer where information is stored, and the business logic layer between them. This middle layer verifies whether the data is correct, calculates values, determines the next steps in the process, and triggers subsequent actions, such as sending a notification or transferring information to another system.

Separating the logic from the interface and the data has practical significance: when a company’s operations change—for example, the purchase approval threshold—it is sufficient to modify the rules rather than rebuild the entire application.

Depending on the tool, the logic can be written in program code, in the workflow system configuration, or, in simpler cases, in spreadsheet formulas. Low-code and no-code platforms allow you to describe it visually, without programming.

Business logic examples

  • Calculations – order value with a discount based on the amount or the customer, VAT, and bonus calculations.
  • Data validation – verifying that the request contains all required information and that the end date does not precede the start date.
  • Approval Workflows – requests up to a certain amount are approved by a supervisor, and those above that amount are additionally approved by the CFO.
  • Status Changes – once an invoice is approved, its status changes to “payable,” and the system creates a task for the accounting department.
  • Restrictions and permissions – who can edit a document, who can only view it, and at what stage of the process.

Business logic vs. business rules

A business rule is a single, specific rule, such as “a purchase request exceeding 10,000 PLN requires the director’s approval.” Business logic is a broader concept: it encompasses all such rules as well as the way the system applies them—that is, the order in which conditions are checked, calculations are performed, and actions are carried out as a result. Rules are therefore components of business logic, and the latter describes how they work together to form a functioning process.