Should I use my ERP's built-in AP automation or buy a dedicated AP platform?

Partly structural: an ERP optimizes for being the system of record - ledgers, posting, reporting - and AP capture/workflow/exception handling is one of dozens of modules, not the whole product. Dedicated platforms put their entire engineering focus on capture accuracy, approval flexibility, the invoice workspace, vendor communication, and exception handling. ERP vendors close some of the gap each release, but the focus asymmetry persists - which is why "it's coming next release" rarely fully lands.

The "cheap now, expensive later" tax: manual correction of mediocre capture, AP headcount that grows with volume because throughput-per-person doesn't, approval bottlenecks and the chasing they create, exception handling done in bare ERP screens without context, and close delays from a backlog the native tools can't clear. None of these appear on the native module's price tag (it's "free"), but they show up in the AP team's hours and the days-to-close.

There's no universal number, but the inflection is usually somewhere in the hundreds of invoices per month, earlier with multi-entity coding or high exception rates, later with clean homogeneous invoices. The better signal than volume is throughput: if adding invoices means adding AP people, native has stopped scaling.

Symptoms checklist: AP headcount rising with volume, approval bottlenecks and chasing, high capture-correction rates, exceptions worked in spreadsheets, multi-entity coding done by hand, a close that's late because of AP backlog, and no unified place for invoice image plus approval plus conversation. Two or three of these means you've outgrown it.

Roadmap promises slip and, even when delivered, native capture tends to lag dedicated tools because of the focus asymmetry. If AP pain is real today, the cost of waiting (headcount, close delays) usually exceeds the cost of buying - and a dedicated layer can stay even if the native feature eventually matures. Don't run the business on a release note.

Include in both: license/subscription, implementation, and - critically - the manual-labor tail. Native's "free" module still carries correction hours, AP headcount growth, and close-delay costs; the dedicated platform carries subscription but reduces those. A fair TCO counts the people-time native leaves on the table, not just software line items.

Stronger capture across format diversity, configurable/maintainable approval routing, a unified invoice workspace (image, approval, conversation), proactive exception and duplicate handling, vendor communication, and an immutable audit trail built for AP. ERP workflows route and post; dedicated platforms do the AP work around the posting.

Frame it as throughput and risk, not redundancy: the ERP stays the system of record; the AP layer raises invoices-per-FTE, shortens the close, reduces errors and duplicate-payment risk, and produces audit-ready trails. The justification is the headcount you don't add and the close days and adjustments you remove - measurable against the manual tail native leaves.

The native module processed transactions but didn't remove the work: capture still needed correction, approvals still got chased, exceptions still ate hours, and volume growth translated straight into headcount. "We have AP in the ERP" isn't the same as "AP scales without people" - the latter takes a tool focused on the work, not just the posting.

Breakeven is where the labor and close-delay savings exceed subscription. With even modest AP team size and volume, the headcount-avoidance and faster-close value typically clears a dedicated platform's cost - run it on your own invoices-per-FTE and days-to-close, not a generic ROI calculator.

Embedded OCR handles clean, repeat layouts; dedicated AI capture generalizes across format diversity and improves from corrections, lowering the exception rate that drives manual work. The metric that matters is exception/correction rate on your real invoice mix - a few points of difference compounds into real AP hours at volume.

Stampli is the dedicated layer designed to sit on the ERP, not replace it - ERP-native by design, mirroring your structure at field level so coding, matching, and approvals happen in a purpose-built workspace and post clean to the ERP. Stampli AI on average performs 87% of finance work across 2,700+ unique fields (always with human review before posting), which is the throughput-per-person lift native modules don't deliver. The pitch isn't "rip out your ERP's AP" - it's "let the ERP be the system of record and let a focused AP engine do the AP work."