Accounts payable mistakes that quietly drain cash

Honestly, your ability to pay bills on time is one of those boring, unglamorous things that keeps a company alive. Nobody throws a party for the AP department. But miss a few payments and watch how fast everything unravels.

In accounting terms, accounts payable covers everything your company owes: materials, inventory, rent, utilities, services. Money flowing in matters, obviously. But money flowing out to the right people at the right time? That’s what keeps suppliers shipping, landlords happy, and your reputation intact.

I’ve been thinking about this a lot lately because AI tools are flooding into finance departments. And here’s my concern: if your AP workflow is a mess today, automating that mess just means you’ll produce errors at machine speed.

Let’s talk about the mistakes that actually trip companies up.

Batch invoice entry feels efficient but isn’t

When your accounting team has a pile of invoices to enter, batching them feels like the smart move. Knock them all out at once. Less context switching. Faster. But it creates a problem you won’t notice until you need to. Entering invoices one at a time builds a clean paper trail. If your company gets audited, for any reason, you want every single transaction documented individually. You want clear timestamps. You want to see exactly who entered what and when. SAP Concur’s research found that 1.29% of invoices businesses process are duplicates, each averaging $2,034. Batch processing makes these duplicates harder to catch. One-at-a-time entry forces someone to look at each invoice individually, which is exactly the kind of friction that prevents fraud and catches errors before they become expensive.

And here’s the thing about photocopies: don’t let your AP team pay from a copy. Ever. Between the time an invoice arrives and when payment goes out, things change. Credits get issued, quantities get adjusted, terms get renegotiated. If someone pays from a photocopy of the original, they might pay the wrong amount. Or worse, pay the same invoice twice.

These handling mistakes point to something bigger. Most AP departments don’t have a structured system tracking every step of the payment process. Here’s how Tallyfy helps finance teams build reliable AP workflows:

Solo AP operator problem

When you’re trying to cut costs, having one person handle all AP duties sort of seems reasonable. It isn’t.

A single overworked person paying your company’s bills will make more mistakes than a team. That’s not a knock on them. It’s math. Fatigue, multitasking, and the sheer volume of transactions guarantee errors. Plus, concentrating all financial authority in one person creates risk. They control your company’s cash outflows, your vendor relationships, your credit standing.

If that person is juggling AP alongside other responsibilities, bills sit unpaid. Not because they don’t care, but because they’re buried.

In our conversations with finance operations teams, this dedicated approach consistently reduces errors and missed payments. One e-commerce team we worked with had 80+ monthly close tasks spread across multiple people and business days. They tracked everything from A/P aging checks across 4 different carriers to missing W-9s. The complexity demanded dedicated coordination, not a single overworked employee.

APQC research shows organizations lose 0.8% to 2% of total disbursements to duplicate or erroneous payments. That’s real money walking out the door. A dedicated AP team catches these. A lone operator buried in other work? Probably not.

Open purchase orders are ticking time bombs

Most AP invoices come from purchases: goods, materials, services. You use purchase orders to track what’s been ordered and what still needs ordering. Standard stuff.

Here’s where companies trip up. After receiving goods and paying the invoice, somebody needs to close that purchase order. The cycle is done. But if nobody closes it, the purchase order sits open. And open purchase orders create a real risk of issuing payment twice.

You definitely don’t want to rely on your suppliers to tell you that you’ve paid double. That’s an awkward conversation at best. At worst, it signals to vendors that your financial controls are weak and janky, which isn’t the reputation you want when negotiating terms.

This connects directly to the procure-to-pay process and why getting the full cycle right matters. Every step from requisition to payment closure needs to be tracked.

Late payments wreck relationships you need

Your AP commitments need to be met on time and in full. Research on late payment patterns paints a grim picture of how common this problem is and how much damage it causes.

There are plenty of reasons payments go out late. Bills get misfiled. Data entry errors push things into wrong categories. Staff turnover leaves institutional knowledge gaps. Sometimes you just don’t have the cash.

Every invoice that arrives, paper or electronic, lists a due date or payment terms. If the timeline is too tight, your AP person needs to pick up the phone and call their counterpart. Find a solution that works for both companies. That conversation is infinitely better than a missed payment.

Not paying on time can wreck your credit standing with that supplier, and others, for years. I’m not exaggerating. Supplier networks talk. If you get a reputation as a late payer, you might find yourself unable to source the raw materials or inventory you need to operate. I learned this the hard way at Tallyfy. Automated payment deadline reminders and clear approval workflows are what separate reliable AP departments from chaotic ones.

Can you recover from chronic late payments? Rarely.

Paying bills on time is the single most important job of your AP department. Full stop.

Communication breakdowns compound everything

Communication failures in AP happen in two directions: between your company and suppliers, and within your own team.

Suppliers will call to verify invoice receipt or confirm payment schedules. These calls are routine but can be misunderstood or mishandled if your team isn’t prepared for them.

The internal breakdowns are worse. Without clear procedures, your AP staff doesn’t know what their colleagues have already handled. One person assumes another paid an invoice. Nobody did. Months pass. Now you’ve got an angry supplier and a damaged relationship.

One reinsurance company we worked with faced exactly this. Their month-end financial process required at least 5 different people to complete sequential tasks, with some steps requiring completion of earlier ones before the next could begin. Without visibility into who owned which step, invoices sat in limbo. Tallyfy gave them a way to see exactly where each invoice sat in the process and who was responsible for what.

Look, this is probably my biggest frustration with how most companies run AP. The tools exist to prevent these breakdowns. A proper workflow system means everyone sees where every invoice stands. No guessing, no assuming, no “I thought Sarah handled that.”

When AI meets a broken AP process

Here’s where I get a bit contrarian. The AP automation market is projected to hit $11 billion by 2030, and 72% of finance leaders view accounts payable as the obvious starting point for AI deployment. My question is: starting point for what, exactly?

Turns out, if your process is broken, AI will automate the brokenness. Faster duplicate payments. Faster misfiled invoices. Faster communication breakdowns.

Less than 5% of AP departments are fully automated today. That means 95%+ are still running on manual processes with all the problems we’ve talked about. Before you throw AI at the problem, fix the fundamentals:

• Define who handles what at each stage
• Create clear handoff points between steps
• Build in checkpoints that catch duplicates before payment
• Set up deadline visibility so nothing slips through

To be fair, some teams can run both tracks at once. This is exactly why we built Tallyfy the way we did. The process definition comes first. The automation layer sits on top. You can’t automate what you haven’t defined.

Getting the foundation right

The boring truth about accounts payable is that it rewards discipline over cleverness. Something I’ve noticed across industries is that every mistake I’ve described comes from taking shortcuts: batch entry, solo operators, open POs, late payments, communication gaps.

Proper supplier onboarding feeds clean data into AP. Structured workflows prevent the handoff failures. Deadline tracking catches late payments before they happen. And when you do add AI or automation, it amplifies a process that already works instead of scaling one that doesn’t.

Stop worrying about mistakes your AP department might make by giving them the structure to avoid those mistakes from the start.

Accounts payable workflow templates

Example Form

Accounts Payable Invoice Request Form

Use this form to submit a vendor invoice for payment. Provide complete vendor and invoice details to

6 fields

View template

Example Procedure

Invoicing Client(s)

1Set up invoice from your template

2Fill in client and invoice details

3Gather everything that's billable

4Build out the full invoice

5Get someone to review before sending

+2 more steps

View template

Example Procedure

Internal Purchase Order Request

1Submit Purchase Order Request Form

2Finance Manager: Review Standard Purchase Order (Under $10k)

3Update Procurement System Status to Rejected

4Notify Employee: Purchase Order Rejected

5Generate Official Purchase Order Number (Standard PO)

+10 more steps

View template