Invoice Approval Process: A Guide for UK AP Teams

AP teams shouldn’t have to spend their day chasing invoice approvals. But in many UK businesses, that’s precisely what happens.

Invoices arrive by email, get saved into folders, then bounce around in threads until someone has time to respond. It only takes one missing cost centre or unclear approval chain to hold everything up.

A structured invoice approval process takes the pressure off UK AP teams. It captures invoices as they arrive, validates the data, and automatically routes them to approvers using predefined rules and service-level agreements (SLAs).

Approvers can review and sign off on invoices remotely using mobile or digital signatures, and escalate exceptions so invoices don’t sit in limbo. Once signed off, approved invoices are posted to enterprise resource planning (ERP) software with a complete audit trail.

In this guide, we’ll break down what a structured invoice approval workflow looks like, how automation compares to email-based approvals, and the key controls and metrics that help UK AP teams keep invoices moving.

Table of contents

• What is an invoice approval workflow or process?
• Artefacts, roles & systems
• Manual vs automated approval (comparison)
• How invoice approval works (step-by-step)
• Metrics & controls that matter
• Mobile & remote invoice approval 
• UK case study snapshot: Owens Group / Glenkeir Whiskies
• FAQs
  

What is an invoice approval workflow or process?

An invoice approval workflow (also known as an invoice approval process) is the repeatable procedure for reviewing and authorising supplier invoices before they are posted and paid.

It ensures every invoice is legitimate, accurate, correctly coded, and compliant with company policy before funds leave the business. In UK accounts payable (AP) teams, it also supports the consistent handling of VAT, supplier master data checks, and proper authorisation based on spend thresholds.

For most organisations, invoice approval procedures sit between invoice receipt and payment execution. Workflow may vary by business size and sector, but the goal stays the same: to establish a standardised, policy-driven process for vendor invoice approval that minimises delays and prevents avoidable errors.

Artefacts, roles & systems

Before UK AP teams can improve billing approval performance, it helps to map the moving parts. Most invoice delays can be traced back to one of three things: missing artefacts, unclear ownership, or disconnected systems.

Artefacts

The invoice approval process usually relies on a set of related documents and data points, including:

• Supplier invoices received as PDFs, scans or EDI documents
• Purchase orders (POs) and goods received notes (GRNs)
• Contracts and service agreements (particularly for recurring spend)
• Coding details, including general ledger (GL) account, department, cost centre, project, and tax codes
• Budget and spend controls, which often determine who must approve the invoice and in what order

Roles

In most UK SMEs and mid-market firms, invoice approvals aren’t handled by one person. Instead, they’re spread across the finance team and the wider business. The people typically involved in invoice approval may include:

• Requester (the person who raised the purchase request or arranged the service)
• Cost-centre owner (responsible for managing spend within a team or department)
• Budget holder (authorises spend against a budget line)
• AP controller/finance supervisor (ensures policy compliance and processing accuracy)
• Substitutes or delegated approvers (covering annual leave, sickness or travel)

When roles aren’t defined clearly, invoices may bounce between teams or sit untouched while AP personnel try to identify the correct approver.

Systems

Even in lean finance teams, invoice handling usually spans several systems:

• Invoice capture software/IDP (intelligent document processing) to ingest invoices and extract data
• Approval engine to route invoices based on rules and thresholds
• ERP or accounting software (such as NetSuite or Sage 200)
• E-signature/digital signature tools for approvals that require explicit sign-off

Manual vs automated approval (comparison)

Most teams don’t choose a manual invoice approval process; they inherit it. Email approvals, spreadsheet trackers, and shared folders can work at low volume, but cracks begin to show as operations scale.

Here’s how manual and automated approaches to invoice approval compare:

Automated billing approval reduces the need for chasing and back-and-forth communication. Instead of relying on individual knowledge (e.g. “send it to Sarah for sign-off”), the workflow applies consistent rules and records to each approval.

How invoice approval works (step-by-step)

A high-performing invoice approval workflow follows a consistent sequence from intake to payment readiness. The steps below are typical in UK businesses and align well with how finance teams manage supplier risk, VAT, and delegated spend authority.

1. Capture & validate 

The process starts as invoices arrive via email inboxes, PDF attachments, scanned paper or EDI feeds. This is the stage where many invoice approval procedures break down in manual systems, as data entry is slow, fields are missing, and errors creep in.

At this first step, an automated solution can:

• Ingest invoices from email/PDF/EDI
• Extract key data fields such as supplier name, invoice number, invoice date, totals, VAT and payment terms
• Validate details against master data (supplier record, payment terms, bank information where applicable)
• Check for PO numbers or contract references
• Flag duplicates using combinations like vendor + invoice number + amount
• Identify exceptions (e.g. missing PO, VAT inconsistencies, mismatched totals)

Learn more about invoice data capture.

2. Route

Once the invoice is validated, it must be routed to the correct approver(s). Routing is also where many teams apply controls to ensure vendor invoice approval follows segregation of duties (SoD) requirements.

In an automated billing approval model, consistent rules can be created based on:

• Invoice amount thresholds
• GL code, cost centre, department or project
• Supplier category (utilities vs services vs capex)
• PO vs non-PO invoices
• Approval path design: serial, parallel or hybrid

A strong invoice approval workflow will also include:

• Delegation during absence, so progress doesn’t stop when someone is away
• SLAs and escalation rules, ensuring ageing invoices trigger reminders and follow-up
• A structured approval matrix aligned to your organisation’s invoice approval policy

3. Approve

For finance teams under pressure, faster invoice approval is only valuable if control remains intact. The approval experience must support both speed and accountability.

Approvers need sufficient context to green-light invoices quickly and confidently. At a minimum, they should be able to review:

• Invoice details and coding
• Supporting documents (PO, GRN, contract)
• Any highlighted exceptions or variances
• Budget and cost-centre context

E-/digital signatures can be included in the approval process if an organisation’s controls require explicit confirmation, or if there is an internal audit preference for signed authorisation.

Choosing an invoice approval system with mobile access and one-click actions also means approvers can progress invoices without waiting to return to a laptop or office.

4. Post & pay

Once approved, the invoice can be posted to your ERP and queued for payment processing. A connected invoice approval workflow can:

• Write approved invoice data back into the ERP, including coding and VAT details
• Trigger payment runs in line with payment terms and schedules
• Archive invoice documents and supporting records in a central repository
• Record the entire approval history as part of the audit trail (timestamps, approvers, actions and comments)

Integrated document storage reduces manual rekeying and ensures that a posted invoice remains traceable back to its original documents and approvals.

Upstream checks and downstream follow-through 

Invoice approval is one step in the wider invoice-to-pay process. It works best when approvals connect cleanly to the controls that precede them and to the checks that occur after payment.

• 3-way matching confirms that the invoice matches the purchase order (PO) and the goods received note (GRN) within agreed tolerances before being sent for sign-off.
• Reconciliation confirms the invoice has been settled correctly, supporting month-end close, reporting, and audit requirements.

When these steps align properly, fewer invoices are held as exceptions, and your AP team has better visibility from receipt through to payment.

6 ways to automate invoice approvals

From the simplest routing to fully automated approval processes, find the digital workflow that fits your organization!

Download now

Metrics & controls that matter 

To keep invoice approval on track, teams need to be able to see and report on where invoices are getting stuck, how long approvals take, and how often rework is happening.

Here are some useful metrics to track:

• Approval cycle time (invoice received → invoice approved)
• On-time payment % (aligned to supplier terms and internal payment runs)
• Touchless % to approval (how often invoices pass validation and approvals without intervention)
• Exception ageing (time spent in exception status)
• Rework rate (how often invoices bounce back for corrections)
• Duplicate detection rate (how many duplicates are identified before posting)

These metrics show how well the workflow is performing, but the process still needs controls to keep invoice approvals consistent. Common controls include:

• Segregation of duties (SoD)
• Policy rules that enforce required fields and evidence
• E-/digital signatures (where needed)
• Full audit trail across every invoice for approval

Mobile & remote invoice approval 

Remote working is now routine for many UK organisations, and hybrid roles are common across finance, procurement and operational teams. According to industry research, more than half (53%) of UK accountancy and finance professionals currently have a hybrid working setup.

Email, one click and e-/digital signatures 

To keep SLAs intact, approvals need to be easy to complete wherever approvers are working, using tools such as:

• Email-based approvals that allow approvers to review and action quickly

• Mobile and one-click sign-off to prevent bottlenecks when approvers are travelling, on-site, or working flexibly
• E-/digital signatures that support sign-off requirements where explicit authorisation is required by internal policy, audit expectations or governance standards

UK case study snapshot: Owens Group & Glenkeir Whiskies

Across the UK, AP teams are using workflow automation to speed up invoice approvals, reduce paper handling, and strengthen traceability from receipt through to posting.

Owens Group: faster approvals and greater traceability

Owens Group is a UK courier and transport service. To improve procurement and finance workflows, the business moved away from paper-heavy processes and introduced DocuWare Cloud with a Sage 200 integration.

The company wanted to make purchase approvals and invoice handling easier to track, with stronger control and traceability across the process.

Owens Group introduced a customised digital purchase order form and automated approval routing. Requests are now sent to the relevant authorised approvers, who can accept or reject digitally (returning a rejection with a reason). Incoming invoices are captured digitally, indexed and linked to related order documentation.

Invoice data is then transferred into Sage 200, reducing manual entry and speeding up processing for the finance team.

By connecting invoice capture and approvals into a structured workflow, Owens Group can see invoice status, who has approved them, and when — improving visibility for both purchasing and finance.

Read the full Owens Group UK case study.

Glenkeir Whiskies: faster processing for a high-volume AP team

Glenkeir Whiskies Ltd, owner of The Whisky Shop, processes around 300 invoices per month. But the company’s purchasing process was built around paper purchase orders, printed documents and manual checks.

During peak periods, the accounts team would match invoices line by line against goods received notes, then manually enter invoice data into their accounting package. With multiple documents linked to the same purchase, this created delays, added admin workload, and increased the risk of errors.

With DocuWare Cloud and a Sage 200 integration, Glenkeir digitised purchase orders and stored GRNs, enabling its accounts team to access supporting documents in one place. DocuWare also automated the processing of emailed invoices and matched them to GRNs using key data points, removing manual verification.

Invoice approvals now run through an electronic workflow, supporting remote working and speeding up sign-off. Glenkeir’s finance team have reported significant time savings, improved accuracy and cost reductions.

Read the full Glenkeir Whiskies case study.

DocuWare: making invoice approval easier for UK AP teams

Start streamlining your invoice approval workflow today with DocuWare’s secure, rules-driven platform.

Frequently asked questions 

What types of healthcare documents can be processed with IDP? 

Capture the invoice (email/PDF/EDI) and extract key fields, then validate supplier/master data and link the document to its PO or contract; for non-PO invoices, enforce coding to cost centre/project. Check totals, VAT, currency, and due date; run duplicate/fraud checks (e.g., vendor, number, amount); and only then route via the approval matrix.

What is the process of invoice authorisation? 

The invoice is routed to the correct approvers based on thresholds, category, and cost centre, with SLAs, reminders, and escalation. Approvers review coding and any variances, approve (often via mobile/e-/digital signature), after which AP posts to the ERP, queues for payment and archives the audit trail.

What is the 3-way invoice matching process? 

It verifies that the purchase order (PO), goods receipt note (GRN) and supplier invoice agree on quantities, prices and taxes within defined tolerances. If they match, the invoice moves straight through; if not, it’s raised as an exception (e.g., variance, partial receipt) for resolution before approval.

How are non-PO invoices approved? 

By enforcing required fields (cost centre, budget, contract reference), applying stricter thresholds and adding the relevant business owner/budget holder before AP posts the invoice.

How do budgets and cost centres feed into approvals? 

The workflow reads budget and cost-centre data, applies the right approval path, and auto-escalates if approvals would exceed available funds.

How does ERP integration work? 

Master data is used for validation; approved invoices (with coding/VAT) are written back to the ERP, and links to the archived document support audit trails.