What is ERP? How it works and how to evaluate ERP systems

At month-end, someone has to manually reconcile what was ordered, approved, invoiced and paid because finance and procurement run two different, disconnected systems. This is a common pressure point even in organisations that have already invested in enterprise technology.

The reason is usually not a lack of tools. It’s that their ERP – enterprise resource planning software – was never properly configured to match their actual business needs and operations.

ERP is one of the most significant technology investments an organisation can make, but it’s also one of the most frequently underutilised. This guide explains what ERP is, how it works and what you need to understand before evaluating or enhancing your ERP.

What is ERP?

ERP software integrates an organisation’s core operational and financial processes into a single, unified and automated system without the need for manual re-entry. When a buyer raises a purchase order, the inventory module automatically updates stock levels, the accounts payable module creates a payment obligation and the general ledger records the liability.

The key value proposition is a single source of truth. Rather than maintaining separate systems for finance, procurement, HR and inventory, ERP gives every team access to the same real-time data.

ERP isn’t just for large enterprises. Modern cloud ERP solutions serve organisations of all sizes, and UK mid-market businesses are increasingly adopting solutions like Microsoft Dynamics 365, Sage Intacct and Unit4 alongside the larger enterprise deployments of SAP and Oracle.

What does ERP stand for?

The phrase ‘enterprise resource planning’ reflects both its scope (enterprise-wide) and its origin in resource planning, specifically the manufacturing resource planning (MRP) systems that preceded it. Since then, the term has broadened to cover the full range of business functions, not just manufacturing operations.

A brief history of ERP

ERP grew out of material requirements planning systems developed in the 1970s to help manufacturers schedule production and manage inventory. In the 1980s, this extended to broader manufacturing resource planning, and by the early 1990s, Gartner was using the acronym ‘ERP’ to describe systems encompassing finance, HR and procurement.

Cloud-based ERP emerged in the 2000s, and today, ERPs with artificial intelligence capabilities (automated invoice matching, intelligent spend categorisation, predictive procurement analytics) have become increasingly standard.

How ERP works

ERP operates through a shared database that all modules read from and write to. When a procurement transaction occurs, it doesn’t just update procurement data. It simultaneously updates inventory quantities, triggers a payment obligation and records the spend against the relevant category in the general ledger.

ERP vendors usually offer a core set of modules (such as financial management, procurement, HR and inventory) plus optional extensions (including customer relationship management, project management and manufacturing). As ERPs are modular, organisations can select the functions relevant to their operating model.

Core ERP modules explained

Financial management, the foundational module, records all financial transactions in the general ledger (GL), manages accounts payable (AP) and accounts receivable (AR), and supports period-end close. It connects directly to every other module and facilitates forecasting.

Procurement and purchasing manages the purchase-to-pay cycle from requisition to payment. For organisations with significant external spend, it’s often the most important module since it governs how buying decisions connect to financial commitments.

Warehouse and inventory management tracks stock levels, goods receipt and fulfilment. It updates in real time when procurement orders are received or inventory is consumed.

Human resources and payroll manages employee records, payroll and, in some systems, workforce planning. It connects to the GL for payroll posting and cost allocation.

Project management tracks costs and resources against specific projects or contracts. This module is useful for organisations that need to attribute spend to client work or funded projects.

Reporting and analytics surfaces data from all modules in a single reporting layer. It provides the spend visibility, operational dashboards and period-end reports that finance and procurement leaders depend on.

How ERP handles the procurement function

The procurement workflow within an ERP follows a structured sequence: after requisition, approvals and purchase order generation, goods are received, invoice matching is done and payment is organised. Each step is logged and auditable, which matters both for internal controls and for regulatory compliance.

Three-way matching of the purchase order, goods receipt and supplier invoice before authorising payment is one of the most valuable features of an ERP. As we explain in our guide on the procure-to-pay (P2P) process, this prevents payment duplication, catches supply chain setbacks and reduces accounts payable disputes.

That said, ERP procurement modules vary significantly in depth. Some offer full strategic sourcing and supplier management capabilities as part of a wider digital procurement strategy, while others focus only on transactional PO management. Ensure you assess module depth carefully before assuming your ERP covers the full procurement lifecycle.

To optimise operations, especially for purchases made outside the ERP’s native catalogue, Amazon Business integrates with major ERP systems via Punchout. It allows purchases made through Amazon Business to route through your existing ERP approval workflows, which extends e-procurement coverage to a broad supplier catalogue without requiring a separate system.

Cloud ERP vs on-premise

Modern ERP is deployed in three main configurations:

On-premise ERPs are installed and managed on the organisation’s own servers. This was the default for large enterprises but is now increasingly uncommon.

Cloud ERPs are hosted and managed by the vendor, typically on a subscription basis.

Hybrid ERPs run a core on-premise deployment with cloud extensions for specific functions.

Cloud ERP now accounts for the majority of new deployments globally. Gartner projects that 62% of cloud ERP spending will be on AI-enabled solutions by 2027 – a trend that reflects both vendor investment in and customer demand for automation.

For UK organisations considering cloud ERP, General Data Protection Regulation (GDPR) data residency must be taken into account. Any cloud ERP provider processing personal data on behalf of a UK organisation must store and process that data within the UK or in a compliant jurisdiction (a country in the EEA or with a UK adequacy decision).

Why organisations move to cloud ERP

The main drivers for cloud migration are:

• lower upfront capital and operational costs (shifting from CapEx to OpEx)

• automatic updates and security patches

• easier integration with modern software as a service (SaaS) tools

• faster access to AI and automation capabilities.

In turn, the concern most procurement leaders raise is migration risk. Moving from a legacy on-premise ERP to a cloud deployment is a significant project – typically 12 to 24 months for a mid-market organisation, longer for complex enterprise environments. One way to address this is through phased migration: moving one module at a time, or running parallel systems during a transition period.

The business benefits of ERP

ERP offers substantial benefits: data accuracy, cost control, compliance and operational efficiency across the organisation. But these benefits depend heavily on how your organisation adopts and implements the system. According to McKinsey, nearly 70% of ERP transformation programs fall short of realising their potential due to implementation-related setbacks.

ERP for procurement and finance teams

For procurement teams, enterprise resource planning systems enable:

• a consolidated purchase-to-pay workflow

• automated three-way matching

• real-time spend visibility

• an audit-ready purchase order history.

These translate directly into fewer payment errors, faster period-end close and better data for category management and supplier negotiations.

For finance teams, ERP eliminates the manual GL postings that occur when procurement and finance run separate systems. Accurate, real-time GL posting from procurement transactions streamlines period-end close and reduces the supplier disputes and duplicate payments that accumulate when data reconciliation is done manually.

The efficiency opportunity is significant. McKinsey suggests the next wave of procurement automation – including AI-enabled ERP capabilities – could make day-to-day business operations 25–40% more efficient.

Much of that opportunity is only accessible to organisations whose ERP is configured to align with how people actually buy. To better understand how AI is reshaping this space, see our analyses of technology-facilitated procurement transformation and the AI adoption gap in procurement.

ERP implementation: What to expect

ERP implementation is a business transformation project, not a software installation.

The main workstreams involved are process redesign, data migration, training and change management. The most common failure modes are scope creep (adding requirements after the project has started), underinvestment in change management, poor pre-migration data quality and treating ERP as an IT project.

McKinsey’s findings relating to organisational failure to realise ERP benefits are key here. They stress that the primary variable for ERP-enabled scalability and profitability is implementation approach, not vendor selection.

How to set your ERP up for success

Four principles apply regardless of system or organisation size:

Define outcomes before selecting a system. What does success look like for your procurement and finance teams? What processes are broken, what data is missing and what compliance gaps need closing? Start from business needs instead of vendor capabilities.

Clean your data before migration. Data quality problems that exist before migration will be amplified after go-live. Supplier master data, cost centre hierarchies and charts of accounts should all be standardised before the changeover.

Budget for change management at least as heavily as for technical rollout. User adoption is where ERP projects succeed or fail. Training, communication and process documentation are not optional extras.

Plan a phased implementation. Deploying individual regions business units or modules before rolling out reduces risk and gives teams time to learn before the stakes get higher.

How Amazon Business integrates with your ERP

Amazon Business connects directly to ERP and procurement systems via Punchout and API integration, making it an extension of your existing procurement workflow rather than a parallel buying channel.

With Punchout, purchases made through Amazon Business route through your existing approval workflows, use your purchase order numbering protocol and are coded to the right cost centres automatically. This extends your ERP procurement coverage to include a broader supplier catalogue without the need for any additional systems or manual reconciliation.

Amazon Business integrates with major ERP and procurement solutions including SAP Ariba, Coupa, Jaggaer, Ivalua and Basware, among others. For users of SAP or Coupa, the Punchout integration means every purchase triggers the same three-way match and approval process as any other purchase order in the ERP.

Make your ERP investment work harder

Most ERP underperformance is not a technology problem – it’s an adoption and integration issue. Procurement leaders who connect their ERP to modern buying channels and supplement it with spend analytics tools that offer real-time insights consistently outperform those who treat ERP as a fixed, standalone system.

As a starting point, audit your current ERP’s procurement module. If approval workflows are being bypassed, financial reporting is incomplete or supplier integration is limited to a small approved list, the solution may not be a new ERP. Rather, you may need a connected buying solution that expands your system’s coverage and better achieves your overall procurement strategy.

If you use SAP, Oracle or another ERP and want to extend procurement module capabilities without replacing your existing system, explore Amazon Business integrations.

This article was created by professional writers and editors with the assistance of AI-powered tools. AI was used in a supportive capacity only – for example, to aid with translation, content review, and alignment with brand guidelines. All substantive research, editorial decisions, and final approval were performed exclusively by human authors and editors, who retain full editorial responsibility for this publication.