What is a Lastenheft / Pflichtenheft?

In procurement and software projects, the Lastenheft (requirements specification) and Pflichtenheft (functional specification) are two key documents that define and align expectations between a buyer and a supplier.

While the Lastenheft describes what needs to be achieved, the Pflichtenheft details how the supplier intends to fulfill these requirements. Together, they form a critical foundation for project success, contract clarity, and quality assurance.

What is a Lastenheft?

The Lastenheft is created by the buyer or project owner and defines:

• The objectives of the project or product
• The requirements from the user's perspective
• The scope and performance expectations
• Any constraints (technical, regulatory, budgetary)
• The target group and usage context

It serves as the basis for supplier quotations and ensures that all stakeholders share a common understanding of the project goals.

A clear Lastenheft reduces misunderstandings, protects budgets, and increases project success rates.

What is a Pflichtenheft?

The Pflichtenheft is developed by the supplier based on the Lastenheft and outlines:

• How each requirement will be implemented technically
• The architecture, tools, and processes used
• Interfaces, data formats, and functional modules
• The project plan including milestones and resources

Testing and validation procedures

It is typically reviewed and approved by the client before implementation begins. The Pflichtenheft becomes part of the contractual agreement and serves as a reference for delivery and acceptance.

Key Differences Between Lastenheft and Pflichtenheft

‍

‍

Role in Procurement and Software Projects

In procurement, especially for custom software, ERP extensions or SaaS platforms, Lasten- and Pflichtenheft are essential for:

• Transparent tendering and supplier selection
• Objective evaluation of proposals
• Risk reduction through clear scope definition
• Smooth handover to technical teams

Digital Tools for Specification Management

Manual specification documents are prone to versioning issues and lack real-time collaboration. Modern platforms support:

• Collaborative Lasten-/Pflichtenheft creation
• Integrated commenting and approval workflows
• Automated linking of requirements to project milestones
• Change tracking and audit trails

Procurement platforms enables structured RfQs and integrates seamlessly with your documentation process.

Conclusion: Clear Specifications, Better Projects

The combination of a well-structured Lastenheft and a detailed Pflichtenheft enables smooth communication, realistic planning, and better outcomes in procurement and development projects.