Spring Boot makes transaction management dead simple with @Transactional, but things get interesting when multiple methods, nested calls, or services interact with the same transaction.

Two of the most commonly misunderstood propagation modes are:

• Propagation.REQUIRED
• Propagation.REQUIRES_NEW

This post breaks down what they mean, how they behave, and when to use each — with real-world examples and code.

⚙️ What is Transaction Propagation?

In Spring, transaction propagation defines how a method should behave if a transaction already exists.

• Should it join the existing one?
• Should it start a new one?
• Or should it run without any transaction?

That’s what propagation modes decide.

🧩 Propagation.REQUIRED (default)

• Joins the existing transaction if one exists.
• If no transaction is active, starts a new one.
• Rollbacks affect the entire chain.

Code Example:

@Service
public class PaymentService {…