Determine finality requirements: ACH (standard and same-day) is not final — returns are possible for up to 60 days for unauthorized debits; RTP and FedNow are irrevocable once completed; Fedwire is irrevocable same-day.
Determine speed requirements: Standard ACH settles T+1 or T+2; Same Day ACH settles same business day if submitted before NACHA cutoffs (multiple windows); RTP and FedNow settle in seconds, 24/7/365; Fedwire settles same day during Fed operating hours.
Check amount limits: Same Day ACH has a per-transaction cap (currently $1 million); RTP (The Clearing House) has a per-transaction cap (currently $1 million); FedNow also has a configurable cap (default lower, up to $500,000 at launch but subject to change); Fedwire has no practical limit.
Assess cost: ACH is the cheapest rail (fractions of a cent to a few cents); RTP and FedNow cost more per transaction than ACH but less than wire; Fedwire is the most expensive per transaction.
Confirm receiver readiness: Not all banks participate in RTP or FedNow; verify receiver bank participation using The Clearing House's participant directory (for RTP) or the Federal Reserve's FedNow participant list before routing.
Select the rail: use Standard ACH for low-cost bulk payroll/B2B; Same Day ACH for urgent but reversible payments; RTP/FedNow for real-time irrevocable consumer or business payments; Fedwire for large, time-critical, irrevocable B2B or securities settlement.
Known gotchas
ACH debits (pulling money) carry a different risk profile than ACH credits (pushing money); unauthorized debit returns can arrive up to 60 days after settlement, creating significant chargeback exposure for platforms.
FedNow and RTP are separate networks with different bank participation lists; a bank may be on one but not the other — always check both lists if your implementation can route to either.
Same Day ACH cutoff windows are set by NACHA and enforced by the originating bank's ODFI; your sponsor bank may impose earlier internal cutoffs than the official NACHA times — confirm the actual cutoffs with your bank.
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp