Settlement date for a trade date: US equities T+1 on NYSE and Federal Reserve days, or T+n on a caller calendar
Computes the settlement date for a trade date under US equities T+1 (17 CFR 240.15c6-1, compliance date 2024-05-28) counting only days when the NYSE and the Federal Reserve Banks are open, or T+n on a named or caller calendar, and checks an asserted settlement date. The settlement-day rule (NYSE and Reserve Banks both open, so Columbus Day and Veterans Day are skipped) is our inference, not a published settlement calendar, and is labelled so in versions. It does not cover other markets' cycles, bonds/FX conventions, exemptions agreed between parties, or corporate-action dates.
What you get
T+1 across Columbus Day, Juneteenth or a Friday trade is wrong by a day if you only skip weekends.
Call it
Send the JSON body below to https://agents.writerslogic.com/api/v1/settlement-date. An unpaid request answers 402 with the price and how to pay; a request that fails with a 5xx status is not charged.
curl -i -X POST https://agents.writerslogic.com/api/v1/settlement-date \
-H 'content-type: application/json' \
-d '{"settlement":"us-equities","tradeDate":"2026-10-09"}'
Input
| Field | Type | Required | Description |
|---|---|---|---|
settlement | string; one of "us-equities", "custom" | yes | us-equities: T+1 since 2024-05-28 on the us-equities-settlement calendar (2026-2028). custom: cycleDays on calendar/holidays/weekend. |
tradeDate | string; length 0..10 | yes | |
cycleDays | integer; 0..30 | no | custom only. |
calendar | string; one of "us-federal", "us-federal-reserve", "nyse", "us-equities-settlement", "uk-england-and-wales", "uk-scotland", "uk-northern-ireland", "weekends-only", "caller" | no | Named holiday calendar with a source and supported date range (outside it the answer is unsupported), weekends-only (Saturday/Sunday only), or caller (only the holidays you list). |
holidays | array<string; length 0..10>; max 400 items | no | Extra non-business dates YYYY-MM-DD (company closures, a calendar we do not carry). |
weekend | array<integer; 0..6>; max 6 items | no | Non-business weekdays, 0=Sunday..6=Saturday. Default [0, 6]; use [5, 6] for a Friday/Saturday weekend. |
claimedSettlementDate | string; length 0..10 | no |
Example request body
{
"settlement": "us-equities",
"tradeDate": "2026-10-09"
}
Result
The response is { "data": ..., "_provenance": ... }. data carries these fields; _provenance is a signed W3C Verifiable Credential with a C2PA-style manifest, checked free at POST /api/v1/verify-provenance.
| Field | Type | Required | Description |
|---|---|---|---|
status | string; one of "pass", "fail", "unknown", "unsupported" | no | pass: every rule held. fail: a rule was violated (see witnesses). unknown: the input lacks the evidence to decide. unsupported: outside what this engine covers. Missing evidence is never a pass. |
settlementDate | string | no | |
weekday | string | no | |
cycleDays | integer | no | |
tradeDateIsTradingDay | boolean | no | |
skipped | array<object> | no | |
reason | string | no | |
witnesses | array<object> | no | |
versions | object | no | Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile). |
limits | array<string> | no | |
deterministic | boolean | no | Always true: pure code, no model. |
Pay and connect
Available through: x402 (USDC on Base), MCP. MCP clients reach it through the calendar-deadline-kit package.
Machine-readable
- This agent as JSON (schemas, example, OpenAPI operation)
- Free signed sample response
- OpenAPI 3.1 · Catalog · Index of every agent