From payroll processing to connected HR platform: how Group S redefined HR service delivery

Apr 14, 2026

employee experience
Microsoft Azure

For many HR service providers, technology has quietly become a brake on progress. Systems that once did the job well are now holding organizations back: difficult to adapt, hard to connect, and out of step with what employers and employees expect today. Group S felt that tension every day. And instead of accepting it, they chose to rework the foundations of how HR services are delivered. They needed a platform that enables advisors to focus less on execution, and more on proactive guidance and collaboration. In April 2026, that ambition became reality with the go‑live of Sienna: a new, cloud‑native HR platform built on Microsoft Azure, developed in close partnership with delaware and Microsoft.

Challenge

HR advisors expected to deliver proactive, connected HR services, in a sector constrained by legacy platforms.

Solution

Sienna: a cloud-based, open, and AI-enabled HR platform, built on Microsoft Azure, that connects systems, simplifies work and supports advisors.

Results

A successful go‑live in April 2026, laying the foundation for a new generation of HR services for Group S and beyond.

Challenge

Group S processes more than 270,000 payroll calculations every month, supported by over 700 HR professionals across 19 offices. Their reality is complex, and becoming even more so.

Payroll, HR, finance, ERP, CRM and e‑government are increasingly intertwined. Compliance grows stricter with each legislative cycle. And employers no longer want HR partners who simply know the rules: they expect partners who anticipate questions and provide guidance.

Classic payroll platforms were never designed for that role. They’re excellent at calculation, but less helpful at connection. They create friction where HR advisors need flow, and soak up time that should be spent with clients.

The pressure comes from three directions:

Legacy platforms that are rigid, siloed and hard to adapt.
Rising expectations from employers, employees and regulators.
Ecosystem complexity, where HR tools must work together instead of alongside each other.

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The HR sector needs modern, scalable and open platforms so advisors can focus on clients and employees, not on fragmented systems or manual workarounds. By embedding intelligence from the start, we want to strengthen our service quality and better support our people in their roles. This go‑live is an important milestone, and the starting point of a broader transformation.

Koen Van Loo, Chief IT & Digital Officer at Group S

Solution

Sienna was created as more than a replacement for existing tools. It was designed as the orchestrating layer of a broader HR ecosystem: one that can evolve over time, connect existing and future solutions, and support the way HR professionals actually work.

Built cloud‑native on Microsoft Azure and integrated with EverESSt, Group S’s payroll engine, Sienna brings everything together in one modern environment. EverESSt delivers payroll accuracy and depth, and Sienna makes that information usable, connected and actionable.

From the first production release, HR professionals can manage:

employer and employee data
digital contracts
payroll finalization and post‑payroll follow‑up
reporting and operational dashboards

Security, compliance and multilingual support are built in by design, not bolted on later.

What truly sets Sienna apart is how AI is embedded at the core of the platform, not added on later. AI helps reduce repetitive tasks, surfaces relevant information at the right moment and supports HR professionals in navigating complexity. The goal is not automation for its own sake, but creating more space for human judgement, context and advisory interaction.

Sienna is:

Open by design: integrating seamlessly with HR, finance, ERP, CRM and e‑government systems
Intelligence‑enabled by default: using AI to support daily work and anticipate needs, rather than react to issues
Built to scale: ready to evolve as services, partnerships and expectations change

This is not an IT replacement project. It is our shared ambition to structurally modernize how HR services are organized and to help set the direction the sector takes in the years ahead. Sienna was built as a lever for renewal: not just for Group S, but for any HR organization that wants to compete in a market where openness, integration and intelligence are the new baseline. We are proud to stand alongside Group S as they lead the way.

Juan Staes, Partner at delaware

Results

The go‑live of Sienna in April 2026 marks a tangible first milestone in how HR services are delivered at Group S. For HR advisors, daily work is far less fragmented across systems. Critical HR processes now come together in one connected environment, reducing manual intervention, avoiding double work and creating much more continuity across the HR lifecycle.

The impact is practical and immediate:

HR professionals spend less time navigating systems and more time supporting clients
Information is easier to access and reuse, improving consistency and quality
Processes flow more naturally from payroll into follow‑up and reporting, supporting advisory work
Employers benefit from faster responses and more contextual support, not just correct calculations

In short, Sienna doesn’t replace payroll excellence: it builds on it. By removing friction from the operational layer, Group S has created the space for HR advisors to focus on proactive guidance, stronger relationships and a better experience for both employers and employees. At the same time, the platform remains flexible enough to support future services and integrations.

Group S & delaware

This outcome reflects who Group S is as an organization. As one of Belgium’s leading HR and payroll service providers, Group S chooses to use technology as a strategic lever to strengthen its advisory role and better support employers and employees.

That ambition took shape through close collaboration with delaware and Microsoft. From design to go‑live, the partners combined complementary strengths: Group S’s HR expertise, delaware’s experience in translating HR processes and service models into scalable, AI‑enabled platforms, and a secure, scalable cloud platform on Microsoft Azure. delaware’s long‑standing collaboratioan with Microsoft, recognized in 2025 with the Microsoft Partner of the Year Award in Belgium, provided a solid foundation of expertise and trust. The result is a platform designed not just for today’s needs, but to grow with Group S and the wider HR ecosystem in the years ahead.