A perfectly ordinary invoice lands and everything matches: Supplier, amount... nothing flags.
Eleven days later, it's still waiting for approval.
Perhaps the approver is on leave. Maybe the request is buried in an email thread that has already been marked as read. Perhaps it was forwarded to the wrong person. Or perhaps nobody is entirely sure whose sign-off is required next.
The invoice itself may be fine. But the process around it has stalled.
Invoice approval delays usually happen because routing rules are unclear, approvals rely on manual email handoffs, or finance cannot see who is currently responsible for the bill. Other invoices are delayed for a valid reason, such as a missing purchase order, incorrect coding or a discrepancy that needs investigating.
A routing delay means a valid invoice is waiting for the process to move it forward.
An exception delay means something needs to be resolved before approval can continue.
Email treats both problems in much the same way: somebody in finance has to find the invoice, work out what went wrong and start chasing people. A structured invoice approval workflow separates the two, routes clean invoices automatically and gives every exception a visible owner.
An invoice approval delay is the time a supplier invoice spends waiting for review and sign-off, usually caused by unclear routing, manual email handoffs, or no shared view of who is responsible next, rather than by slow approvers. Effective fixes include role-based routing with authority thresholds, automatic escalation and delegation when an approver is away, and separating genuine exceptions such as PO mismatches or missing coding from invoices merely waiting for attention. Automating these methods can cut approval times from weeks to under two days.
Invoice approvals rarely become delayed because everybody involved has decided not to act.
More often, the process depends on people remembering to forward emails, interpret approval rules and follow up manually. Each handoff creates another opportunity for an invoice to disappear from view.
Six patterns are responsible for most approval delays. For a full walkthrough of how a modern invoice approval workflow is structured end-to-end, see our invoice approval workflow guide.
An approval email has to compete with meetings, customer requests, internal messages and everything else in an approver's inbox.
It arrives with no position in a visible queue. It may have no deadline attached. Once opened, it can disappear among dozens of messages already marked as read.
Finance then has no way to know whether the approver has reviewed it, missed it or assumed somebody else would take care of it.
The process becomes:
Send. Wait. Follow up. Wait again... Resend. Repeat.
At sufficient volume, accounts payable stops processing invoices and starts coordinating inboxes.
Some businesses have formal approval policies. Others have a collection of habits.
Invoices are sent to the person who approved something similar last time. Larger bills may be forwarded upwards, but nobody is certain at which threshold that should happen. Department heads change, reporting lines move and rules that made sense two years ago fall out of date.
That may be manageable with two invoices a month. At two hundred, it becomes a standing tax on the finance team's time, paid repeatedly through the same avoidable questions:
If the approval logic lives in people's heads, every invoice has to rediscover its route.
A workflow built around named individuals stops working when one of those individuals is on holiday, travelling, ill or no longer responsible for that area.
Without delegation or a backup approver, the invoice just waits.
Somebody taking leave is normal. What causes the delay is an approval process that had no planned route around their absence.
Some approvals are delayed because the approver cannot make a sensible decision from the information provided.
They may not recognise the supplier. The invoice might be missing a purchase order reference, project code, receipt or explanation of the expense. A vendor's trading name may differ from the name already held in the accounting system.
The approver replies with a question. AP contacts another department. A second email thread begins.
The invoice is no longer waiting for a yes or no. It is waiting for context.
A good approval workflow should place the invoice, supplier details, coding, purchase order, supporting documents and prior comments in front of the approver at the same time.
Not every delayed invoice should be approved faster.
A mismatch between an invoice and purchase order, suspected duplicate, incorrect supplier detail or missing goods receipt may be a legitimate reason to pause payment.
Things go wrong once the workflow identifies the problem but does not assign responsibility for resolving it.
The invoice enters an exception queue. Procurement assumes finance owns it. Finance assumes the budget holder owns it. The approver sees a discrepancy but does not know what to do next.
A controlled hold becomes an invisible backlog.
The costliest delay is often the one nobody can see coming.
Without a single view of invoices in progress, finance only discovers that a bill is stuck when:
By then, every available option is a rushed one.
Before changing the workflow, identify which type of delay is occurring.
| What you can see | Likely cause | Practical fix |
|---|---|---|
| A clean invoice has sat with one person for several days | No reminder, escalation or delegation rule | Add a response target, reminders and a backup approver |
| The invoice keeps being forwarded between managers | Approval authority is unclear | Document approval thresholds and route by role |
| The wrong person repeatedly receives invoices | Rules no longer reflect the organisation | Review departments, cost centres and authority levels |
| The invoice is waiting for a PO, receipt or coding | Missing information before approval | Validate required data before routing |
| A mismatch has been identified but nothing happens | The exception has no resolution owner | Assign exception types to named teams or roles |
| Finance discovers the delay during the payment run | No central status visibility | Introduce an invoice dashboard and overdue reporting |
| Low-value invoices take as long as high-risk purchases | Too many approval layers | Simplify thresholds and remove unnecessary sign-offs |
| Approvals stop whenever somebody is away | Workflow depends on an individual | Add delegation, substitutes and role-based routing |
This diagnosis prevents a common mistake: adding more reminders to an invoice that cannot yet be approved.
Reminders solve inaction. They do not solve missing information, policy ambiguity or an unresolved discrepancy.
Approval delays tend to push work into the two windows finance can least afford to lose: the month-end close and the payment run.
An invoice still waiting for approval at month-end either holds up the close or has to be accrued and reconciled later. Neither is catastrophic in isolation. Repeated across dozens of invoices, both create unnecessary work and weaken confidence in the numbers.
The pressure lands particularly heavily on financial controllers.
Reconciliations sit waiting on approvals that should have happened weeks earlier. Outstanding liabilities are less clear. Late decisions have to be reconstructed from email threads, forwarded attachments and comments made across several systems.
The same gap that slows the close also weakens the audit trail of who approved what, when and with which supporting information.
Payment runs introduce another kind of pressure. Late approval can mean a rushed final check, a missed early-payment discount or a late supplier payment.
For businesses that depend on a small number of critical vendors, the risk is operational as well as financial. Before automating its approval process, illumin's finance team manually watched high-priority vendor bills because late payment could cause essential services to be withdrawn. Its invoices could take weeks or even months to approve; after introducing ApprovalMax, the typical approval time fell to less than two days. In cases like that, invoice approval is more than an administrative process. It is part of keeping the business running.
AP automation removes the repeated routing decisions and manual handoffs from the approval process.
Each invoice follows a predefined route based on rules such as:
Approvers still make the decision. Automation does not replace their judgement.
It replaces the forwarding, searching, reminding and reconstructing that surround the decision.
A structured workflow sends the invoice to the correct approver and then moves it to the next stage without finance forwarding another attachment.
Sequential approvals can enforce a required order. Parallel approvals can collect independent decisions without making one person wait unnecessarily for another.
At Letgo, moving away from manual approvals reduced the weekly time spent managing them from four hours to around ten minutes. Approval times became 96% faster, while finance no longer needed to chase approvers or route documents manually.
Every invoice should show:
That changes the conversation from “Where has this gone?” to “This has been waiting with the project approver for three days.”
The first question sends someone hunting through inboxes. The second tells them exactly who to prod.
Email approval becomes particularly fragile when managers work across sites, projects, subsidiaries or time zones.
Le Contrôleur had a construction and engineering client processing up to 650 invoices a month, with project managers spread across Canada. Email approvals took an average of 15 days. After moving the process into ApprovalMax, approval times were reduced by more than half and weekly AP administration fell from 10–15 hours to around four or five. Managers did not suddenly become less busy. The route to them became clearer and easier to act on.
Automation should not force every invoice down the clean approval route.
Instead, it should identify exceptions early and send them to the person able to resolve them. For example:
The aim is to bring the right human into the process at the point where their judgement is needed, rather than removing people from it.
Email can prove that somebody wrote “approved”, but the surrounding context may be scattered across replies, attachments and inboxes.
A structured workflow records the invoice, approval route, comments, decisions and timestamps together.
At BMI Group, replacing email with chained, structured approvals saved approximately 60 hours a week across 15 people. It also increased the proportion of purchasing following the standard process from 50% to 100%. The gain was consistent control, not only faster processing.
You do not need to redesign the whole accounts payable function at once.
Start with the point where invoices currently spend most of their time. If you want more day-to-day tactics for tightening up the process itself, see practical ways to take control of your invoice approval process.
Measure the time between:
An overall average can hide the real problem.
If nine invoices are approved within one day and one waits for three weeks, the average may still look acceptable. Track the median as well as the slowest 10% of invoices to expose the delays that create month-end problems.
Document:
Map the intended process, not the improvised process people have grown used to.
A complete, valid invoice should not wait behind invoices that need investigation.
Define the checks that need to happen before approval begins, such as:
Then create a clear resolution route for each failure.
Avoid workflows built entirely around individual names.
Use roles such as department head, project manager, budget owner or financial controller, supported by rules for amount, supplier, entity and category.
Named users will still occupy those roles, but the approval logic will survive staff changes and absences.
Email can notify an approver that work is waiting. It should not be the system in which the approval process is reconstructed.
Give approvers one place to review the invoice, supporting documents, coding, purchase order details and earlier comments.
The less hunting required before a decision, the faster a considered decision can be made.
Set a realistic approval target for each stage.
If no action is taken:
Escalation should be proportionate. A routine £200 invoice does not need to land with the CFO because somebody missed one notification.
Finance should be able to see:
The aim is to intervene before the payment run or month-end, not during it.
Before rolling the process out widely, replay a representative set of recent invoices through the proposed rules.
Include:
A workflow has not been tested properly if it only works for the easiest invoice.
The most useful measure goes beyond how many invoices were approved.
Track:
The typical time between an invoice entering approval and receiving final sign-off.
How long the slowest 10% of invoices take. These are usually the invoices causing payment and close problems.
This shows whether the delay occurs during validation, approval, exception handling or posting.
The proportion of invoices that exceed the agreed turnaround for their current stage.
The percentage of invoices requiring manual investigation, together with the most common reasons.
A high number may indicate outdated routing rules, insufficient delegation or unrealistic approval targets.
This is one of the most useful operational views ahead of a payment run.
Do not use these metrics merely to publish a league table of “slow approvers”. A slow approval stage may be caused by missing information, unnecessary policy or poor routing rather than the individual receiving the request.
Measure the process first.
A reliable workflow should provide:
Most importantly, it should continue enforcing the approval policy when somebody is away, the invoice is unusual or month-end pressure arrives.
That is when the process is truly tested.
An invoice approval delay is the time a supplier invoice spends waiting to be reviewed and authorised for payment. It may be caused by manual routing, an unavailable approver, unclear approval rules, missing information or an unresolved exception.
Email provides no reliable queue, workflow order or shared status view. Requests can be buried, forwarded to the wrong person or left waiting when somebody is unavailable. Finance then has to identify the current owner and chase the approval manually.
There is no universal target because approval requirements vary by risk, value and complexity. A routine, correctly coded invoice may take hours, while a large or exceptional purchase may reasonably take longer. The important measures are whether each stage has an agreed target and whether delays are visible before they affect payment or month-end.
No. It replaces manual routing, follow-ups and record-keeping. Approvers still review the invoice and make the decision, but they receive the right request, in the right order, with the information needed to act.
A structured workflow can redirect the request to a delegated or backup approver. It can also escalate the invoice after a defined period rather than leaving it untouched until the original approver returns.
Yes, provided the exception process is designed properly. Automation can identify missing data, duplicate warnings, PO mismatches and other issues, then assign them to the person or team responsible for resolution. It should not automatically approve an invoice that requires investigation.
It moves approval work out of the close by routing invoices as they arrive. Finance can see which invoices remain outstanding, why they are waiting and who needs to act before month-end begins. The associated approval history also remains available for reconciliation and audit.
An invoice approval delay is rarely proof that the people involved are inherently slow.
It is usually evidence that the process has no dependable order, no substitute when somebody is unavailable, no owner for exceptions and no shared record of what is waiting on whom.
Define the approval rules. Separate valid exceptions from avoidable waiting. Move the decisions out of email threads. Give finance one view of every invoice in progress.
The invoices were always going to be approved eventually.
Automation stops them sitting in a queue that nobody could see.
Explore how ApprovalMax supports invoice approval workflows and accounts payable automation, or take the ApprovalMax product tour to see the approver experience.