> ## Documentation Index > Fetch the complete documentation index at: https://developers.staging01.melio.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Check fast payment eligibility > Checks which faster-than-standard delivery options a payment between two of the entity's accounts is eligible for, without creating one. Eligibility depends on the originating account, the receiving account, and the `amount` (minor units, cents). The response has one entry per fast option valid for the receiving account, for example `same-day-ach` and `rtp` for ACH, or `express-check` and `overnight-check` for check. ## OpenAPI ````yaml /openapi.json post /tools/fast-payment-eligibility openapi: 3.0.3 info: title: Melio Payouts API version: '1.0' description: > Self-serve payouts API. Partners onboard an Entity, which is the business (organization plus owner, with the details required to be payment-eligible), then attach accounts (internal accounts and external accounts) and make payments. ## Resource ids Every resource has an opaque, prefixed id that is stable for the life of the resource: `ent_` (entity), `pay_` (payment), `acct_` (account, internal or external). Ids are Melio-issued; treat them as opaque strings and never parse or construct them. To attach your own identifier to a resource, use `externalId`. ## Pagination List endpoints are cursor-paginated and always return results newest-first (`createdAt` descending). The response envelope is: ```json { "data": [ /* resources */ ], "hasMore": true } ``` Page through results with `limit` (1 to 50, default 50) plus a cursor: - `startingAfter=`: return the page immediately **after** the given resource id (the next, older page). This is how you walk forward through a list. - `endingBefore=`: return the page immediately **before** the given resource id (the previous, newer page). `startingAfter` and `endingBefore` are mutually exclusive. The cursor is a resource id you already received (e.g. the `id` of the last item on the current page), not an index. Keep requesting the next page until `hasMore` is `false`. ## Filtering & sorting Ordering is fixed (newest-first); there is no `sortBy`. To narrow a list, filter it. Each list endpoint documents its own filter parameters (there is no generic query language). Date-range filters use bracket suffixes and accept RFC 3339 timestamps: `created[gte]`, `created[lte]`. Filter by your own identifier with `externalId`, and by metadata with `metadata[]=` (matches resources whose metadata contains every supplied key/value pair). Filters combine with AND and compose with pagination. ## External ids Every created resource accepts an optional `externalId`, your own unique identifier for the resource (≤255 chars, letters/digits/`-`/`_`). It is unique per partner per resource type: reusing one returns `409 DUPLICATE_EXTERNAL_ID`. Use it to correlate Melio resources with records in your system and to look resources up (`?externalId=`) without storing Melio ids. `externalId` identifies a *resource*; it is not a request-deduplication key (that is the `Idempotency-Key` header, below); the two are complementary. ## Idempotency Send an `Idempotency-Key` header on every create so retries are safe: the original response is replayed instead of creating a second resource. It is required on `POST /payments`. ## Metadata Most resources accept a `metadata` object: free-form string key/value pairs that Melio stores and returns verbatim but never interprets. Limits: up to 50 keys, key ≤40 chars, value ≤100 chars. Use it to stash your own structured context on a resource; it is also filterable (see above). ## Melio Sonar Session Token Write endpoints optionally accept a `Melio-Sonar-Token` header: a signed session token minted by the MelioSonar SDK on the end user's device, carrying device signals used for risk evaluation. Omit it when no SDK session is available. contact: name: Melio Platform External API email: platform@melio.com servers: - description: Production url: https://api.melio.com/v2 - description: Staging01 url: https://api.staging01.melio.com/v2 security: [] tags: - name: Entities description: >- A business you onboard and operate on behalf of: its profile, compliance details, and per-operation limitations. - name: Accounts description: Accounts the entity pays from (internal) and payees it pays to (external). - name: Payments description: >- Money moved from an internal account to an external account, and their lifecycle. - name: Tools description: >- Pre-flight calculators for fees, fast-payment eligibility, and delivery estimates. No resource is created. - name: Webhooks description: >- Your single endpoint for event notifications, and the events you can subscribe to. paths: /tools/fast-payment-eligibility: parameters: - $ref: '#/components/parameters/MelioEntityId' post: tags: - Tools summary: Check fast payment eligibility description: > Checks which faster-than-standard delivery options a payment between two of the entity's accounts is eligible for, without creating one. Eligibility depends on the originating account, the receiving account, and the `amount` (minor units, cents). The response has one entry per fast option valid for the receiving account, for example `same-day-ach` and `rtp` for ACH, or `express-check` and `overnight-check` for check. requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/FastPaymentEligibilityRequest' example: originatingAccountId: acct_3f2504e0-4f89-41d3-9a0c-0305e82c3301 receivingAccountId: acct_9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d amount: 125000 responses: '200': description: >- Fast-payment eligibility decisions, one per fast delivery preference for the receiving rail. content: application/json: schema: $ref: '#/components/schemas/FastPaymentEligibility' example: originatingAccountId: acct_3f2504e0-4f89-41d3-9a0c-0305e82c3301 receivingAccountId: acct_9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d amount: 125000 currency: USD eligibilities: - deliveryPreference: same-day-ach eligible: true - deliveryPreference: rtp eligible: false '400': description: Validation error or invalid account type content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '404': description: Entity or account not found content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' security: - ApiKey: [] components: parameters: MelioEntityId: name: Melio-Entity-Id in: header required: true description: >- Entity the request operates on — an entity id (`ent_`) or `me` (the partner's sole entity). schema: type: string schemas: FastPaymentEligibilityRequest: type: object required: - originatingAccountId - receivingAccountId - amount properties: originatingAccountId: type: string description: Internal originating account id (acct_), the debit account receivingAccountId: type: string description: External receiving account id (acct_), the credit account amount: type: integer description: The prospective payment amount to check, in minor units (cents). currency: type: string default: USD FastPaymentEligibility: type: object required: - originatingAccountId - receivingAccountId - amount - currency - eligibilities properties: originatingAccountId: type: string receivingAccountId: type: string amount: type: integer description: Echoes the requested payment amount, minor units (cents). currency: type: string eligibilities: type: array description: > One entry per fast delivery preference valid for the receiving external account. Empty when the rail has no fast variants. items: $ref: '#/components/schemas/FastPaymentEligibilityDecision' ErrorResponse: type: object required: - error properties: error: $ref: '#/components/schemas/Error' FastPaymentEligibilityDecision: type: object description: >- Whether a single fast delivery preference is available for the prospective payment. required: - deliveryPreference - eligible properties: deliveryPreference: type: string enum: - same-day-ach - rtp - express-check - overnight-check - instant-domestic-wire - instant-virtual-card description: >- A faster-than-standard delivery preference valid for the receiving external account. eligible: type: boolean description: > True when this fast delivery preference can be used for the prospective payment. When false (including when the eligibility engine is unavailable), only the receiving rail's standard-speed preference should be used. Error: type: object required: - type - code - message properties: type: type: string description: >- Coarse, machine-readable error category. Branch on this to handle a whole class of failures without enumerating every `code`. enum: - invalid_request_error - authentication_error - authorization_error - not_found_error - conflict_error - rate_limit_error - service_unavailable_error - internal_error code: type: string description: Machine-readable error code. enum: - VALIDATION_ERROR - INVALID_ACCOUNT_TYPE - INVALID_DELIVERY_PREFERENCE - MCC_REQUIRED - GOODS_RECEIVED_REQUIRED - IDEMPOTENCY_KEY_REQUIRED - FEE_CALCULATION_FAILED - UNAUTHORIZED - NOT_FOUND - NO_ACTIVE_API_KEY - DUPLICATE_ENTITY - DUPLICATE_ACCOUNT - DUPLICATE_PAYMENT - DUPLICATE_EXTERNAL_ID - ACCOUNT_IN_USE - BUSINESS_NOT_ELIGIBLE - PAYMENT_NOT_EDITABLE - PAYMENT_NOT_CANCELABLE - IDEMPOTENCY_KEY_REUSED - IDEMPOTENCY_KEY_IN_PROGRESS - IDEMPOTENCY_STORE_UNAVAILABLE - INTERNAL_ERROR message: type: string description: Human-readable error message. details: type: object description: Additional error context (e.g. field-level validation failures). securitySchemes: ApiKey: type: apiKey in: header name: api-key ````