List available payment methods for a vendor with GET /v3/payments/options?vendorId={id}&amount={amount}
Create an ACH payment with POST /v3/payments, specifying processDate as the next US business day if submitting after 10 AM PT
For 1099 contractor compensation payments, include a standardized PAYROLL description in the payment per NACHA rules effective March 20, 2026
Monitor payment status by listening to the payment.updated webhook event or polling GET /v3/payments/{id}
Handle failed ACH returns by checking the return reason code in the webhook payload and initiating a corrected payment or contacting the vendor
Known gotchas
Pay Faster ACH submitted after 10 AM PT must use the next US business day as processDate — same-day requests after the cutoff are rejected
From March 20, 2026, NACHA mandates a standardized PAYROLL descriptor for ACH payments to consumer accounts for wages or contractor compensation; missing this can trigger return codes
BILL v2 endpoints for payments are in LTS mode and no longer receive new features; use v3 endpoints exclusively for new integrations
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