Running accounts payable inside an ERP means the payables function lives in the same system as the ledger, purchasing, inventory and everything else. The appeal is obvious and largely real: one system, one set of data, no integration to maintain, and a purchase order that is genuinely the same object payables matches against. The cost is also real and less discussed: ERP payables modules are usually less pleasant to use than specialist tools, change slowly, and are configured rather than adopted. This page is what you gain, what you give up, and the situations where each answer wins, written for a business small enough that the choice is still open.
What a single system genuinely gains
No integration to build, break or reconcile. The purchase order, the receipt and the invoice are the same records rather than copies. Reporting spans the whole chain without joining anything. For a business that already runs an ERP, these are substantial and often decisive.
What you give up
Interface quality and speed of change. ERP payables modules tend to be functional and dated, approvals are often clumsy on a phone, and improvements arrive on the vendor's schedule. Since approver adoption decides whether a payables process works, that is not a cosmetic complaint.
When each wins
If you already run an ERP and its payables module is tolerable, use it: the integration you avoid is worth more than the interface you gain elsewhere. If approvals are the bottleneck and the module is the reason, a specialist front end feeding the ERP is a legitimate answer. On the worked example on this site, 400 invoices at three touches of six minutes with a 12% exception rate is 134.4 hours a month: $4,300.80 at a $32 loaded rate, $10.75 an invoice and $51,609.60 a year.
Questions people ask about erp accounts payable
Is ERP payables worth buying an ERP for?
No. Payables alone never justifies an ERP; the decision is made for other reasons and payables comes along with it.
Can we put a specialist tool in front of an ERP?
Commonly done, and it reintroduces the integration you chose the ERP to avoid. Worth it when approvals are the constraint, not otherwise.
Do small businesses run ERPs?
Increasingly, in lighter cloud forms. The trade above holds at every size; only the numbers change.