Least-Cost Routing

Least-Cost Routing exists because dual-network debit cards give the merchant (via their acquirer) a choice about which network processes the transaction — and that choice carries material cost implications.

How Dual-Network Debit Works

Most consumer debit cards in markets like Australia, Canada, and the US carry two network affiliations: a global scheme (Visa Debit or Mastercard Debit) and a domestic network (eftpos, Interac, STAR, NYCE, etc.). When a tap-and-go or chip transaction is initiated, the merchant's payment terminal and acquirer jointly determine which network to route through.

Without LCR, the terminal defaults to the scheme network — which typically carries higher interchange and scheme fees. With LCR enabled, the acquirer compares the cost of each available network and routes to the cheaper one automatically.

Three Different Mechanisms, Not One Mandate

"LCR" is used for at least three distinct regimes, and they are not interchangeable:

Australia: LCR here is a self-regulatory industry framework — built by AusPayNet under RBA oversight, not a formal statute. The RBA endorsed LCR in 2015 and "strongly supported" industry calls for acquirers to provide it in 2017; Parliament threatened regulatory action if banks did not implement it voluntarily. There is no single mandate date — the industry rollout of merchant-selectable contactless routing ran from late 2018 into 2019. eftpos routing is typically cheaper than Visa/Mastercard debit for domestic card-present transactions, particularly in grocery, fuel, and QSR. See the full Least-Cost Routing breakdown for the AusPayNet/RBA history and PSP implementation detail.

United States: The Durbin Amendment's implementing rule, Regulation II, is a genuine federal mandate — but it mandates network choice, not cost routing. Issuers must enable at least two unaffiliated debit networks per transaction and cannot block merchant routing choice between them; this applies to every debit issuer regardless of size. It does not require anyone to actually route to the cheaper network — that optimization layer is built separately by acquirers and PSPs on top of the enabled choice.

Canada: Interac debit carries lower interchange than Visa Debit or Mastercard Debit for domestic transactions, with no regulatory routing mandate behind it — a commercial routing decision, not a legal requirement.

Operator Considerations

LCR is typically configured at the acquirer or payment terminal level, not in the merchant's application code. Operators evaluating PSPs should ask explicitly about LCR or routing-optimization support, whether it's enabled by default, and — for US merchants specifically — whether the PSP is actually cost-optimizing across the Reg II-enabled networks or merely satisfying the enablement requirement.