The cost comparison between ACH and card payments appears straightforward at the transaction level. ACH processing costs $0.25 to $1.50 per transaction as a flat fee or a small percentage (typically 0.5% to 0.8% with a cap). Card processing costs 2.5% to 3.5% of the transaction amount, with the rate varying by card type, interchange tier, and whether Level 2/3 data is present. On a $10,000 B2B invoice, ACH costs $1.50; card costs $250 to $350. The savings case for ACH seems obvious — and for large transactions, it is.
But the cost calculation changes at lower transaction values and when you account for the full operational picture. ACH transactions take 2 to 4 business days to settle, while card transactions settle in 1 to 2 days. ACH returns (the equivalent of chargebacks) can occur up to 60 days after the transaction, creating cash flow uncertainty. ACH bank account verification adds friction to the enrollment process — particularly for new customers who must provide routing and account numbers and complete a micro-deposit verification. Card payments, by contrast, offer immediate authorization, faster settlement, and chargeback protections that shift some dispute risk to the card network.
The break-even point depends on your specific fee structure and operational costs. As a general framework: for transactions above $2,500, ACH is almost always cheaper — the percentage-based card fee exceeds the flat ACH cost by a wide margin. For transactions between $500 and $2,500, ACH saves money on processing fees, but the 2-day settlement difference has a cash flow cost that partially offsets the fee savings. For transactions below $500, the fee difference is modest ($5 to $15), and the operational simplicity of card payments — immediate authorization, no bank verification, buyer-friendly experience — often outweighs the incremental cost.
The optimal strategy for most B2B companies is not ACH-only or card-only — it is a method-steering approach that directs each transaction to the lowest-cost method based on amount, customer type, and payment context. High-value invoices ($5,000+) are steered toward ACH with incentives like early-payment discounts. Mid-range invoices ($500-$5,000) offer both methods with ACH positioned as the default. Recurring payments (subscriptions, service agreements) default to ACH for predictable cash flow. One-time payments and new customer transactions default to card for immediate settlement and reduced enrollment friction.
Payment method steering requires a platform that supports both ACH and card processing, presents payment options intelligently in the customer portal, and tracks the fee impact of each payment method by customer and transaction type. The data from the first 90 days of steering typically reveals that shifting 20 to 30 percent of card volume to ACH saves 0.8% to 1.5% of total processing costs — without alienating customers who prefer card payments for convenience, rewards, or cash flow management on their side.