B2B payments: procure to pay

Accounts payable (AP, the team and process that pays a company's bills) looks like the mirror image of receivables. It isn't quite. A buyer's AP team spends most of its week deciding whether to pay: is this a real supplier, a proper invoice, for goods we received, at the agreed price, approved by someone allowed to approve it, going to an account that really belongs to the supplier? Moving the money is the last step, and the easiest.

Four ideas organize what I've learned so far.

1. AP is a control function first and a payments function second. APQC's median cost to process one invoice is $5.78, and $3.55 of that is people (data year not shown). Ardent Partners puts the exception rate (invoices that fail matching or validation and need a human) at 18.4% for all but the best-performing fifth of enterprises (January 2026). The newest duties are controls too: since June 22, 2026, Nacha requires every business that originates ACH credits to monitor its own payments for fraud. And tax law makes AP a reporting agent: 1099s and backup withholding in the US, T4A slips and input tax credit evidence in Canada.
2. The invoice, not the payment, is the unit of work. Every AP benchmark is per invoice: cost, cycle time, exception rate. Payments are batched, so one check or ACH credit pays many invoices. Legal clocks start at receipt of a "proper invoice", and in Canada the invoice is also a tax document for the buyer.
3. The buyer chooses the rail, and is often paid to choose the one that costs the supplier most. A virtual card (a card number issued for one payment) costs the buyer nothing and earns it a rebate, while the supplier pays 1.75% to 2.95% plus $0.10 in Visa commercial interchange (April 2026). A check costs the buyer $2 to $4 but keeps the cash in its account for days longer. The Federal Reserve names the conflict plainly: buyers want to hold cash, suppliers want it fast.
4. Speed is a priced asset, and the buyer owns the clock. "2/10 net 30" (2% off if paid within 10 days, otherwise due in 30) is worth about 37% a year to a buyer who takes it. Hackett Group put the DPO (days payables outstanding) of the 1,000 largest US public companies at 59 days for 2024. Supply chain finance lets a buyer stretch terms while a bank pays the supplier early, which is why accounting standard setters now force disclosure.

Put together, the product is a control system that happens to move money: it decides what to pay, when and by which rail, and proves afterwards that each decision was right.

Three things make this harder than the B2B platforms you know:

• The fraud loss lands on your customer. When a buyer pays a fraudster after a "we've changed banks" email, US law usually leaves the loss with the buyer, and the real supplier is still owed. The vendor master (the buyer's record of each supplier, bank details included) is the control point, not the rail.
• Every lever has a supplier on the other side. The buyer's rebate is the supplier's card fee; the buyer's float is the supplier's DSO (days sales outstanding).
• The slowest steps belong to people outside AP: business approvers, the receiving dock, procurement.

This is the buyer's side of the same payment; for the seller's side see B2B payments: order to cash.

The procure-to-pay map

The textbook flow is requisition, order, receipt, invoice, match, approve, pay. In practice it runs to eleven steps, three teams outside AP own some of them, and the "cycle time" most people quote starts only at step 4.

1. Requisition. Someone asks to buy; a budget owner approves the spend. Non-PO spend (services, utilities, software) skips steps 1 to 3 and is approved after the invoice arrives.
2. Purchase order. Procurement issues the PO (the buyer's written commitment: item, price, quantity, terms) by EDI 850, PDF or a supplier portal.
3. Receipt. The dock records the goods, or the requester confirms the service. Stalls: nobody enters the receipt, so step 5 can't pass.
4. Invoice capture. The invoice arrives on paper, as a PDF, an EDI 810, through a portal or an e-invoice network, and is keyed, scanned or ingested. Stalls: it lands in a shared inbox with no PO number, addressed to the wrong legal entity or (in Canada) without a valid GST/HST number, and goes back to the supplier.
5. Match. Two-way (invoice against PO: price and quantity) or three-way (invoice against PO and receipt).
6. Exceptions. A variance beyond tolerance, no receipt, a closed PO, freight that wasn't on the PO, a dispute over wrong or short goods. Resolved by auto-approving inside tolerance, routing to the requester, asking for a credit memo, or waiting. Stalls: this is the backlog, about 18% of invoices at most enterprises (Ardent).
7. Approval. Routed by amount, cost center and category under a delegation-of-authority matrix (who may approve what, up to which amount), then posted as a liability. Stalls: non-PO invoices waiting on business approvers who don't see AP as their job.
8. Scheduling. A payment proposal picks invoices for the next run: on the due date, early for a discount, or later. Fraud and tax holds sit here: recently changed bank details, a name that doesn't match the account, a missing W-9.
9. Payment run. Treasury or AP approves the proposal, two people release it in the bank portal, and each payment goes out by check, ACH, wire, instant payment or virtual card. Stalls: a weekly or twice-monthly run can add up to two weeks, whatever happened upstream.
10. Remittance. The supplier is told which invoices the payment covers: a check stub, ACH addenda, an email, a portal. To AP, the invoice is now "paid".
11. Reconciliation. The payment clears, the bank statement is matched to AP's payments, and year-end tax reporting runs off the totals.

On timing: APQC's median from receipt of invoice to payment transmitted is about 15 days, and top performers take about half that. A second APQC measure stops at "approved and scheduled": 2.8 days or less for the top quartile, a week or more for the bottom, which is why bottom performers miss 10-day discounts (CFO.com on APQC, August 2022). Ask which definition any "cycle time" uses before you compare two of them.

Rail cheat sheet: paying suppliers

Sources (as of Oct 2026): AFP's 2022 Payments Cost Benchmarking Survey (2021 data; labor has risen since), FedNow 2026 fees, Nacha on Same Day ACH (the cap rises to $10M on September 17, 2027) and credit-push fraud, Visa interchange (April 18, 2026), Visa's older straight-through merchant sheet, GSA SmartPay, AFP's 2026 fraud survey highlights, Payments Canada. Canadian per-item prices weren't found.

Why do checks survive? They were still 26% of US and Canadian B2B payments in 2025 (AFP), and in AFP's 2026 fraud survey 68% of organizations paying vendors by check said vendors require it. Buyers have their own reasons, which the 2025 survey lists: smaller vendors' reluctance, "reluctance to see funds leave their accounts instantly", and difficulty confirming bank details. In Canada, 22% of commercial firms value being able to stop a cheque after issuing it (Payments Canada, 2024 data). From inside AP, a check is a cheap, stoppable payment that keeps the cash longer; the cost and the fraud risk land elsewhere.

The mirror: who wins on each lever

Almost every AP lever is a supplier cost on the other side. Read this next to the order-to-cash guide.

Sources (as of Oct 2026): Visa interchange, GSA SmartPay (FY2025), Visa surcharging requirements, CFIB, UCC 4A-202, and AP payment companies' public filings for the fee and float patterns.

The buyer's best deal is usually the supplier's worst, and an AP fintech's revenue often sits exactly in that gap.

What doesn't transfer

Money flows

AP money moves in four streams: the cost to process invoices, the cost (or income) of sending payments, the value of timing them, and what providers take in between.

Cost to process an invoice

APQC's total cost to process AP: $2.05 per invoice for top performers, a median of $5.78 (also reported as $6.00), $10.00 for the bottom (data year not shown). Ardent's 2025 figures: $9.84 for most enterprises, about $2.07 for "Best-in-Class" (the 20% with the lowest costs and fastest cycles). At 50,000 invoices a year, moving from APQC's median to the top saves about $190,000: real money, and small next to one BEC loss or a year of missed discounts.

Cost to send, by rail

Run one $25,000 invoice through it (US, interchange only; add the supplier's acquirer markup and network fees):

Sources: AFP's cost survey (2021 data), Visa (April 18, 2026), GSA SmartPay. At bank level a FedACH item costs $0.0035 and a tier-1 Fedwire transfer $0.97 (FedACH, Fedwire, 2026); what banks charge customers isn't public. Cross-border is its own world: a $20,000 small-business payment cost 1.6% on average in 2025 (FSB).

Rebates

The US federal card program spent $39.4B in FY2025 and earned agencies $471M in refunds, about 1.2% blended across purchase, travel and fleet cards. One multi-state cooperative contract with a large bank issuer, amended October 1, 2025, pays 135 basis points on standard volume, 123 on large-ticket spend, 33.75 for national volume, and a prompt-payment rebate of up to 44 basis points that falls 1 point for every day the buyer leaves the balance unpaid, reaching zero at 45 days. My reading, to confirm with an issuer: rebates are priced across the whole program, and the issuer also earns from how long the buyer takes to pay it. The card program prices the buyer's float to the day; most AP departments don't price their own float at all.

Early-pay discounts

"2/10 net 30" offers 2% for paying 20 days early. The implied annual rate is 2/98 × 365/20 = 37.2% simple, about 44.6% compounded; "1/10 net 30" is about 18.4%. A buyer whose cash or credit line costs less should take it: $500 on a $25,000 invoice. Capture depends on approving inside 10 days, which the APQC top quartile's 2.8 days allows and a bottom-quartile week doesn't. Dynamic discounting slides the discount by the day from the buyer's own cash: at a 12% annual target, paying 20 days early earns 12% × 20/365, about 0.66%.

Supply chain finance

In reverse factoring the buyer confirms an invoice is valid, and a bank or platform pays the supplier early at a discount priced off the buyer's credit. The buyer pays the funder at maturity, often after extending terms (say from 60 to 90 or 120 days). The supplier gets cash below its own borrowing cost but pays the discount, often after its terms were stretched. The buyer gets a higher DPO (days payables outstanding), no interest expense and, if it stays a trade payable, no debt on its balance sheet. The funder earns a spread on buyer risk plus fees. The risk, flagged by the IFRS Interpretations Committee in 2020: if the funder withdraws, months of extended payables fall due at once.

Hackett Group's 2025 survey of the 1,000 largest US public non-financial companies found DPO rebounding to 59 days in 2024, with the top-quartile gap widening. The supplier-side mirror: the Credit Research Foundation's median DSO was 37.5 in Q2 2026 (a different population).

How AP fintechs make money

Four revenue lines, usually combined:

1. Buyer software: subscriptions or per-invoice fees, sold on lower cost per invoice.
2. Per-payment fees, often charged to the supplier for "enhanced" ACH or faster funds.
3. Virtual card interchange net of rebates. Some networks even refund suppliers part of their card fees to stop them refusing cards.
4. Interest on funds held between debiting the buyer and paying the supplier. Outsourced check printing moves the buyer's float to the provider: the buyer is debited at the run, the check clears days later.

Public filings from companies in this space point the same way: payment revenue outweighs software, card interchange is a large part of it, and float income has been shrinking as rates fall. "We pay your suppliers for free" means someone else pays: the supplier through card fees, or the buyer through float it no longer earns.

The power map

Power follows the clock and the rail, and a large buyer holds both.

• Buyer CFO and treasury set terms, rail policy and supplier finance; they earn rebates, float and discounts and bear fraud losses.
• Procurement picks suppliers and can write card acceptance or a surcharge ban into the contract.
• AP rejects invoices, holds payments and makes suppliers use its portal.
• Business approvers are the bottleneck and earn nothing for speed.
• Suppliers want to be paid on time, in full, cheaply, with remittance. Weak against big buyers, stronger when scarce, they pay the card fees, the finance discount and the cost of lateness.
• Banks sell treasury services, Positive Pay and card programs; their security procedures shift UCC 4A losses to the customer.
• Card issuers and networks set interchange and run enrollment campaigns.
• AP networks and hubs own the enrolled-supplier list and the payment status; ERP vendors decide who gets the "pay" button.
• E-invoice networks are weak in North America without a mandate.
• Standard setters and regulators (IRS, CRA, FASB, IASB, Nacha, the Fed, FINTRAC, the Bank of Canada) impose tax, disclosure and rail rules.

Large buyers dictate net 60 to 90 terms, portals, rails and supplier finance; small suppliers comply or lose the account. Government buyers are the exception, because law caps their lateness. The pending Visa and Mastercard settlement (preliminary approval June 9, 2026, final approval pending at this review) would let merchants accept or decline credit cards by category, commercial included, with more surcharge freedom, per Visa's public filing. It would give suppliers a right to refuse commercial cards, not the leverage to use it: virtual card enrollment is negotiated supplier by supplier, and the buyer's contract is still the real limit.

Regulation in practice

For AP, the gap between written and enforced is mostly tax and fraud.

• 1099 thresholds jumped. A July 2025 federal law raised the 1099-NEC and most 1099-MISC thresholds from $600 to $2,000 for payments after December 31, 2025, indexed from 2027; the same floor applies to backup withholding. Royalties stay at $10, gross proceeds to attorneys at $600, and payments to corporations are mostly exempt except legal and medical. Card payments go on Form 1099-K, filed by the settlement entity, whose threshold went back to more than $20,000 and 200 transactions (IRS, 12/2026). Paying a supplier by card moves its tax reporting out of AP.
• Canada's T4A rule is written, mostly unenforced. Fees for services over $500 a year belong in box 048, but the CRA hasn't assessed box-048 penalties since a 2011 moratorium, except for trucking payments from the 2025 tax year (CRA, April 2026).
• Canadian input tax credits are enforced on the invoice. From $100 the buyer needs the tax charged and the supplier's GST/HST number; from $500, also its own name, a description and terms (CRA). Invoice validation in Canada is a tax control.
• Nacha now reaches into AP. Since June 22, 2026, every non-consumer originator of ACH credits must run risk-based processes "reasonably intended to identify" payments that are unauthorized or "authorized under False Pretenses" (BEC, vendor impersonation). Nacha's tips: validate new and changed accounts, verify changes out of band, use dual control, review daily reports of existing payees moving to new accounts. It's enforced through the buyer's bank and doesn't change UCC 4A (Nacha). It's the first ACH rule that puts a monitoring duty on AP itself.
• UCC 4A is enforced by courts, after the fact. The security procedure in the bank agreement decides most cases.
• Supplier finance is visible now. FASB's ASU 2022-04 requires buyers to disclose program terms, the confirmed amount outstanding, where it sits on the balance sheet and, for fiscal years beginning after December 15, 2023, a rollforward. It changes disclosure only, not recognition or measurement. IFRS reporters, including Canadian public companies, have had similar IAS 7 and IFRS 7 rules since January 1, 2024.
• E-invoicing is voluntary. The US has no B2B mandate; DBNAlliance publishes no adoption volumes (FedPayments Improvement). The CRA's 2025-26 plan committed to evaluating e-invoicing for GST/HST compliance; the 2026-27 plan doesn't mention it.

The cost of being wrong

AP mistakes cost in five currencies: cash, double payment, tax, supplier goodwill and audit findings.

• Cash. The FBI's IC3 logged 24,768 BEC complaints and about $3.05B in reported losses in 2025; its Recovery Asset Team froze $679M of $1.16B attempted (58%) in the cases it worked (IC3). In AFP's 2026 survey, 74% of organizations saw BEC attempts; among them, 49% saw wires targeted and 31% ACH credits. In one AFP case a vendor bank change took three payments totaling $150,000, and $915 came back (AFP, May 2026).
• Double payment. After a BEC loss the real supplier is still owed.
• Tax. A missing TIN means a 24% withholding duty and IRS notices; a bad GST/HST number puts the credit at risk.
• Supplier goodwill. Late payments bring dunning, late fees and credit holds. Missed discounts cost about 37% a year and never appear as a line item.
• Audit. A vendor-master change without segregation of duties, or a manual payment that skipped approval, becomes a control deficiency.

The cheapest defense works: in AFP's 2026 survey, 94% of organizations call suppliers back on a number already on record, and 63% rate it "very effective".

Top failure modes

Sources: FBI IC3, Nacha, IRS, CRA, IFRS. Ranking these by volume or cost needs an operator's data; I haven't found any public.

False friends

Sources: APQC, Visa's straight-through merchant sheet, GSA SmartPay (which calls rebates "refunds").

Where my analogy broke

"I assumed AP was the mirror of AR." Writing the order-to-cash guide, I spent most of my words on matching money to invoices, and expected the buyer's side to be the same problem in reverse. It isn't. The hard question in AP comes before any money moves: should we pay this at all? Matching, approval, vendor checks and tax validation are the job; the payment is the by-product.

"Rebates are carrier fees running backwards." In telco, carrier fees flow downstream and stop. Here the issuer pays the buyer a rebate out of the interchange the supplier pays. The buyer is paid to choose the rail that costs its own supplier the most, and nobody involved finds that strange.

"A bank-detail change is a number port." A port has an authority: the losing carrier validates ownership and a central database flips the record. A supplier's bank change is an email and a clerk updating a field, and the receiving bank pays by number whatever the name says. There's no registry to ask, so the control has to live in AP.

"Batching is a throughput trick." In messaging you batch to move volume efficiently. In AP the batch is a treasury decision: weekly runs hold cash, checks add float, and paying early is a choice with a price. The goal isn't fast; it's on time, or deliberately early for a discount.

"Instant payments would land like faster delivery." In AFP's 2025 survey, over two-thirds said faster payments had no impact on their organization, and buyers cited reluctance to see funds leave instantly. Speed is the supplier's want; the buyer's is control of the date.

Self-check: 20 questions

1. Trace a purchase from requisition to reconciled payment. Which four steps stall most? Answer
2. Why is AP a control function first and a payments function second? Answer
3. What does a $25,000 invoice cost the buyer and the supplier by check, ACH, wire and virtual card? Answer
4. What does "2/10 net 30" mean, and what annual rate does taking it imply? Answer
5. Who funds a virtual card rebate, and how does a card contract price the buyer's float? Answer
6. Why can't a supplier that takes cards necessarily take your virtual card? Answer
7. What does "paid" mean to AP, the bank, the card issuer and the supplier? Answer
8. A clerk receives new bank details from a supplier by email. What should happen before the next run? Answer
9. A buyer paid a fraudster after a fake bank change. Who absorbs the loss, and what happens to the invoice? Answer
10. A mailed check was altered. Who pays, and what changes the answer? Answer
11. What can a buyer do after releasing an ACH credit by mistake, and within how long? Answer
12. What did Nacha's 2026 fraud-monitoring rules change for a buyer's AP department? Answer
13. What changed about 1099 reporting for 2026 payments, and why does paying by card move reporting out of AP? Answer
14. Why is invoice validation a tax control in Canada? Answer
15. Who sets match tolerances, payment terms and surcharge caps? Answer
16. Which dated changes from 2025 to 2028 should an AP system store with effective dates? Answer
17. Where does remittance get lost on the buyer's side? Answer
18. What registrations or licenses might an AP fintech that holds buyer funds need in the US and Canada? Answer
19. What would the Visa and Mastercard settlement change for suppliers, and why might it change less than it seems? Answer
20. Name four ways AP fintechs make money, and who pays for each. Answer

Sources

Undated entries were read on October 1, 2026.

Rail operators and payment systems

• Fraud monitoring phase 2, Nacha, 2026; Tips for originators to comply with the 2026 risk management rules, Nacha, Dec 2025; BEC attempts rose sharply in 2025, Nacha, May 2026
• New rules take aim at credit-push fraud, Nacha, Mar 2024; funds availability for non-same-day credits, Nacha, 2026; Same Day ACH limit to $10M, Nacha, Apr 2026
• FRB Services: FedACH 2026 fees, FedNow 2026 fees, Fedwire 2026 fees, FedNow $10M limit (Sep 2025), 2026 fees and enhancements, including Payee Name Verification (Dec 2025)
• Payments Canada: Lynx adopts ISO 20022 (2025), Canadian Payment Methods and Trends 2025, RTR testing and launch

Tax authorities, government buyers and law

• IRS: Instructions for Forms 1099-MISC and 1099-NEC (12/2026), Publication 1099 (2026), proposed regulations, IR-2026-03 (Jan 2026), backup withholding, TIN Matching
• Bureau of the Fiscal Service: Prompt Payment, interest rates (H2 2026), Invoice Processing Platform
• CRA: 2025-26 Departmental Plan, 2026-27 Departmental Plan, Reporting fees for service (Apr 2026), Documentary requirements for input tax credits, Confirming a GST/HST account number
• Federal Prompt Payment for Construction Work Act, Justice Laws; new federal prompt payment legislation, PSPC, Dec 2023
• UCC 4A-202 and 4A-207, Cornell LII
• 2025 IC3 Annual Report, FBI, Apr 2026
• Payment service providers must register, FINTRAC, Jul 2022; retail payments supervision FAQ, Bank of Canada, Aug 2026
• GSA SmartPay statistics, GSA, FY2025
• July 2026 price filing, USPS, Apr 2026

E-invoicing and standards

• FedPayments Improvement: electronic invoices, B2B payments experts launch DBNAlliance, frictions in B2B payments
• DBNAlliance, home page
• Peppol authorities, OpenPeppol
• Supply chain transaction flow and transaction sets, X12

Accounting standards and international bodies

• ASU 2022-04, Supplier Finance Programs, FASB, Sep 2022
• IASB increases transparency of supplier finance, IFRS Foundation, May 2023; reverse factoring agenda decision, IFRS Interpretations Committee, Dec 2020
• G20 cross-border payments progress report, FSB, Oct 2025

Card networks

• Visa USA Interchange Reimbursement Fees, Visa, Apr 2026
• Visa straight-through processing merchant sheet, Visa (older document)
• Supplier Matching Service, Visa Developer
• Merchant surcharging considerations and requirements, Visa, Aug 2023

Industry associations and benchmarks

• 2026 Payments Fraud and Control Survey release, AFP, Apr 2026; 2026 payments fraud outlook, AFP, May 2026
• 2025 AFP Digital Payments Survey, AFP, 2025
• 2022 Payments Cost Benchmarking Survey, AFP, 2022
• APQC: total cost to process AP per invoice, cycle time from invoice receipt to payment (data years not shown)
• CFO.com on APQC: AP cycle time, Aug 2022; duplicate or erroneous payments, Mar 2020
• National Summary of Domestic Trade Receivables, Credit Research Foundation, Q2 2026
• Credit card surcharging, CFIB

Cited without links (the source URL carries a company's name or ticker)

• AFP 2025 and 2026 Payments Fraud and Control Survey key highlights, AFP, Apr 2025 and Apr 2026 (hosted by the underwriting bank)
• State of ePayables 2025, Part Nine: AP benchmarks, Ardent Partners, Jan 2026
• 2025 Working Capital Survey press release, Hackett Group, Aug 2025
• Washington State DES commercial card Contract 00719, Amendment 2, Oct 2025
• Visa Form 8-K on the merchant settlement, Nov 2025
• Annual reports (Form 10-K) of three US AP and corporate-payments companies, FY2024 to FY2026 (secondary: vendor-reported)
• Summary of Studco v. 1st Advantage (4th Cir.), a law firm, Apr 2025