and why the answer shouldn’t surprise anyone, except those who could change it
There is a situation I encounter in AP departments so regularly that it can no longer be coincidence. It has a recurring face: a stack of open invoices that does not get smaller. A team that works every day and feels every evening that it has not really made progress. Suppliers sending reminders. Discount periods expiring. And a manager who does not understand why this is the case, even though the team is working.
This backlog is not a workload problem. It is almost never a capacity problem. And it is definitely not a problem that overtime solves.
It is a structural problem. Usually with a predictable cause. And almost always tied to a leadership decision that was either not made or not consistently implemented.
This article explains why AP backlogs arise, what really lies behind them, and what a CFO must do to change this structurally. Not in six months. Now.
What an AP Backlog Really Means
Before the causes can be analysed, it must be clear what an AP backlog actually signals. Because most managers misread it.
The most common interpretation is quantitative: too many invoices, too little staff, too little time. The derived solution is correspondingly: more staff, more overtime, more capacity.
This interpretation is almost always wrong.
An AP backlog is not a capacity signal. It is a process control signal. It shows that somewhere in the chain between invoice receipt and booking, something is stuck. A step that takes too long. An approval that does not come. A system configuration that requires manual intervention. An interface between departments that does not work.
And because this bottleneck is not removed, the backlog accumulates. Every day new invoices come in. Every day fewer are processed than arrive. The stack grows.
More staff does not solve this. More staff increases capacity before the bottleneck. It does not remove the bottleneck. The backlog grows more slowly, but it grows.
This is the first mental error a CFO must avoid: confusing symptom treatment with root-cause resolution.
The Seven Most Common Causes of AP Backlogs
In my experience from AP mandates there are seven structural causes that account for the overwhelming majority of all AP backlogs. Rarely just one. Usually a combination of several.
Cause 1: The approval process is the bottleneck
This is the most common and least addressed cause. Invoices are not stuck in the AP team. They are stuck in the inbox of managers who are too busy to approve them in time.
The AP team is doing everything right. It processes what it receives. But what it receives arrives late because the approval authority does not treat it as a priority.
The consequence is absurd. The AP team carries the backlog even though it is not the bottleneck. Suppliers send reminders to the AP team even though the AP team is not the cause. And managers ask the AP team about the backlog even though the answer lies in their own inbox.
This is a structural dysfunction that only resolves when leadership reorganises the approval processes. Not when the AP team works harder.
What concretely needs to be done: review approval limits and adjust them downward. Not every invoice over EUR 1,000 needs the signature of the division head. Define delegation rules. And set up escalation mechanisms that trigger automatically when an approval is pending for over 48 hours.
Cause 2: The three-way match fails regularly
The three-way match is the automatic reconciliation between incoming invoice, purchase order and goods receipt. When all three agree, the system books automatically. When they do not, the invoice ends up in a manual clarification process.
In many companies the three-way-match rate is alarmingly low. Between 50 and 70 percent is not uncommon. That means that 30 to 50 percent of all incoming invoices must be processed manually.
Every manual processing costs time. Every manual processing requires communication between AP, Purchasing and Inventory Management. Every manual processing is a potential source of delay.
With 500 invoices per month and a 40 percent manual processing rate, that is 200 invoices that must be individually clarified. That is not a workload a team handles on the side. That is a structural capacity problem generated by an incorrect match rate.
The causes for poor three-way-match rates are almost always systemic. Tolerance limits configured too tightly. Price deviations between order and invoice because order prices are not updated. Quantity deviations because partial deliveries are not correctly booked. Or invoices that arrive without purchase order reference because the procurement process is bypassed.
Each of these causes is fixable. But none of them lie within the AP team.
Cause 3: Invoices arrive without purchase order reference
One of the most common causes of AP backlogs is a structural problem outside the AP team: suppliers send invoices without a purchase order number because the procurement process is not consistently followed.
This sounds like a minor process detail. In AP practice it is a substantial problem. An invoice without purchase order reference cannot be matched automatically. It must be assigned manually, which requires research in the system and frequently a query to the requesting department.
In companies where 20 or 30 percent of invoices arrive without purchase order reference, the AP team spends a substantial part of its time assigning invoices to orders that should have been created before the procurement.
That is wasted capacity. Not because the AP team is inefficient. But because the procurement process does not work.
The solution does not lie in AP. It lies in a binding procurement policy stating that no order is placed without a purchase order number, and in an enforcement mechanism that ensures this policy is followed.
That is a leadership decision the CFO makes. Not the AP team.
Cause 4: System configuration generates manual work
Many AP backlogs have a technical cause invisible to the naked eye. The SAP or Oracle configuration is set up such that processes which could be automated require manual intervention.
Tolerance limits that are too tight generate manual clarification loops for cent deviations. Booking rules not aligned with the actual document structure generate error messages that must be manually corrected. Interfaces between pre-systems and SAP that are not cleanly configured generate transmission errors that must be manually fixed.
In one mandate I supported, an AP team spent two hours daily manually correcting error messages from a poorly configured interface between the inventory system and SAP. Two hours daily in a team of six people are twelve hours per day missing from productive work.
That was not a capacity problem. That was a configuration problem. It was fixed in three days. The backlog began to dissolve within two weeks afterwards.
This type of problem is not visible in selection interviews. It only shows up when one works in the system.
Cause 5: Communication between AP and departments is structurally broken
AP backlogs often arise at interfaces between departments. An invoice sits in clarification because a department query is not answered. A purchase order cannot be assigned because no one in the requesting department answers follow-up questions. A difference between order and invoice cannot be clarified because the responsible buyer is not reachable.
The AP team waits. The invoice remains open. The backlog grows.
These communication problems usually have no bad intent. Departments are busy. Queries from accounting have no high priority. And without a defined service level for answering AP queries, there is no structural mechanism ensuring that answers come in time.
The solution is a defined process that establishes within what timeframe queries must be answered, what happens if not answered, and who escalates when the deadline expires.
That sounds bureaucratic. It is process discipline. And process discipline is the difference between an AP department that functions and one that is behind.
Cause 6: Master data is wrong or outdated
An underestimated cause of AP backlogs is poor vendor master data. Wrong bank details that cause payments to fail. Outdated contacts that cause clarifications to lead nowhere. Missing or wrong payment terms that require manual adjustments.
Every payment that fails because of wrong bank details generates a manual correction process. Every clarification that leads nowhere because the contact no longer exists extends processing time.
In companies with high supplier turnover or little master data maintenance, these problems accumulate into a measurable backlog.
The solution is regular master data review, at least annually, where bank details, contacts and payment terms are actively validated.
This is not a glamorous task. But it belongs to the most cost-effective measures with the highest immediate effect on AP performance.
Cause 7: The team has no clear priorities
The last and in its consequence often underestimated cause is a leadership cause. The AP team does not know in what order it should work.
Without clear prioritisation, an AP team works on FIFO principle: First In, First Out. What arrived first is processed first. This sounds fair and logical.
It is wrong for the organisation. Because an invoice that arrived yesterday and has a discount period expiring in three days is more urgent than an invoice that arrived two weeks ago and has no discount. Because an invoice for EUR 100,000 is more important than ten invoices for EUR 1,000. And because a supplier that has already sent reminders must be clarified earlier than one still waiting.
FIFO ignores all these factors. It treats all invoices equally. Which leads to important invoices waiting as long as unimportant ones.
The result is an AP department that works a lot but does the wrong work at the wrong time.
The solution is explicit prioritisation logic. Which invoices are prioritised daily? By what criteria? Who decides when the criteria conflict?
This logic must be explicitly defined and communicated. Not as expectation everyone should derive themselves. As a process instruction that is clear and binding.
What the Backlog Actually Costs
Before a CFO budgets the necessary structural interventions, they must understand what the existing backlog actually costs. Because the costs are real and quantifiable, even if they appear in no P&L line directly.
Discount losses
The most immediate and easily quantifiable cost element is discount losses. Discounts are risk-free returns realised through punctual payment. A typical 2 percent discount at 14 days payment term corresponds to an annual return of over 36 percent. There is no safe investment that beats this.
An AP team in backlog regularly pays after the discount window. That means not only the lost discount. It means in some cases also reminder fees and late interest.
A company with EUR 10 million annual payables volume and an average discount opportunity of 2 percent potentially leaves up to EUR 200,000 per year on the table if discount periods are systematically not used. That is conservative and excludes late costs.
Supplier relationships
Less directly quantifiable but no less real is the damage to supplier relationships. Suppliers that have to repeatedly send reminders and still are not paid on time react over time. They worsen terms. They prioritise other customers. And in extreme cases they no longer deliver or only against advance payment.
For a company dependent on critical suppliers, this damage can be substantial. It does not show immediately. It accumulates silently and becomes visible when it is too late to counter.
Internal capacity waste
An AP team in backlog spends a substantial part of its time answering reminders, searching invoices, delivering status updates, and managing clarification processes that would not have arisen with a functioning process.
This time is missing for the actual work. This creates a vicious cycle: the backlog generates extra work, the extra work prevents the reduction of the backlog, the growing backlog generates more extra work.
When an AP team of six spends two hours per person daily on reactive backlog work instead of productive invoice processing, that is twelve hours daily missing from backlog reduction.
Audit risk
A structural AP backlog is an audit signal. Auditors who see a large number of overdue liabilities ask questions. About process quality, internal controls, completeness of period-end accruals.
Overdue liabilities can also lead to incomplete accrual bookings at period close, which impairs closing quality. That is an audit risk arising directly from the AP backlog.
Why This Is Not a Team Problem
There is a reaction I hear from managers when I have analysed an AP backlog and name the causes.
"Then the team must get better."
This is almost always the wrong conclusion. And it is dangerous because it directs focus to the wrong problem and simultaneously demotivates the team that is supposed to stabilise the situation.
AP teams in backlog usually work hard. Often they work harder than teams without backlog because they have to manage the backlog and associated reminders and escalations on top of their normal work.
The problem is not laziness or incompetence. The problem is a structure that obstructs their work. Approval processes that are too slow. System configurations that force manual intervention. Communication channels that do not work. Prioritisation logic that is missing.
The team cannot change these structures. They lie outside the team's decision authority. They can only be changed by a manager who has the authority to design processes across departmental boundaries.
That is the CFO task.
Whoever responds to an AP backlog with the demand for better team performance, without addressing the structural causes, does the same as someone who orders a leaking pipe to stop leaking. It does not work. And it creates frustration on both sides.
What Must Be Done in the First Two Weeks
An AP backlog that has built up over weeks does not resolve overnight. But in the first two weeks measures can be taken that stop growth and initiate reduction.
Week 1: Situation picture and prioritisation
The first step is not action. It is understanding. Before anything is changed, the complete situation picture must be established.
How many invoices are in backlog, and how are they distributed by age? Which have active reminders? Which have expiring discount periods? Which are blocked due to missing approvals, which due to missing information, which due to system errors?
This analysis takes one day if the data is available in SAP. It yields a prioritised list that divides the backlog into three categories: clarify immediately due to discount periods or active reminders, clarify this week due to soon-expiring payment terms, and clarify over the course of the next month.
With this list the team works in the first week by priority instead of by arrival. This stops the most expensive part of the backlog first.
In parallel: analyse the approval processes. How many invoices are currently waiting for approval? With whom? Since when? This number is usually surprisingly high and immediately shows where the biggest bottleneck lies.
Week 2: Structural immediate measures
With the situation picture from week 1, the most important structural immediate measures can be identified and initiated.
If the approval process is the main bottleneck: introduce temporary delegation rules that delegate approvals below a defined threshold to the AP team. And establish a binding communication channel that moves approval requests from the email inbox into a system enabling deadline monitoring.
If the three-way-match rate is the main bottleneck: identify the most common mismatch causes and make temporary tolerance adjustments in SAP for the most important suppliers that automatically accept obvious small deviations.
If missing purchase order references are the main bottleneck: an immediate communication to all departments clarifying that from now on no procurement without a purchase order number is accepted. This communication must come from the CFO, not the AP team.
If master data is the problem: identify the most common error sources and clean up master data immediately for the most important suppliers.
These measures do not solve the structural problem completely. They reduce the growth of the backlog substantially and give the team the capacity it needs to systematically reduce the existing backlog.
What Must Be Changed Structurally in the Long Term
Immediate measures buy time. But they do not replace structural solutions. What must be changed long-term depends on the specific causes, but in almost all cases has the following elements.
A defined service level agreement between AP and the departments specifying within what timeframe approvals and clarifications must occur. Without this SLA there is no commitment. And without commitment there is no improvement.
A revised SAP configuration that raises the automation degree. Three-way-match tolerances, booking rules, interface configurations: these are technical settings with substantial influence on manual processing rates.
A binding procurement policy that regulates purchase processes such that invoices without purchase order reference are the exception, not the rule.
A KPI dashboard that reports the most important AP metrics monthly to the CFO: DPO, discount rate, three-way-match rate, invoice processing time, number of overdue liabilities. These numbers must be visible so they can be managed.
And finally: a clear prioritisation logic for the AP team that is not left to individual discretion but exists as a binding process instruction.
What This Has to Do with Leadership
I come back to the starting point. AP backlogs are almost never a team problem. They are almost always a leadership problem.
Not because managers have bad intentions. But because the structural causes of AP backlogs can only be fixed by leadership decisions that cross departmental boundaries.
Adjusting approval limits requires a leadership decision. Making procurement processes binding requires a leadership decision. Changing SAP configurations requires a leadership decision. Introducing service level agreements requires a leadership decision.
The AP team cannot make any of these decisions. It can suggest, communicate, document them. But making them is only possible at the leadership level that has the authority to design processes across departmental boundaries.
That is the CFO level.
A CFO who sees an AP backlog and asks what the team should do better has asked the wrong question. The right question is: what must I as CFO change so the team can do its job?
This question is more uncomfortable. It draws responsibility onto one's own level. And it requires interventions into processes and structures that affect other departments and can create resistance.
But it is the only question that leads to a real solution.
What I Bring
I am Nicole Vekonj, Interim Manager Finance & Controlling. I stabilise AP processes that are behind, not through overtime and appeals to the team, but through structural analysis, identification of the real causes and implementation of measures that work sustainably.
My approach begins with the situation picture. Not with assumptions, not with best-practice frameworks, not with tool recommendations. With the actual data from your system that shows exactly where the backlog arises and why.
If your AP team has been behind for weeks and the previous measures have made no sustainable difference, that is a signal. Not about the team. About the structure.
Briefly describe your situation to me. I will answer honestly whether and how I can help.
👉 Submit a project enquiry: zahlenkompetenz.de/en/contact
