---
title: "Propose Block Trade"
method: POST
path: "/communications/block-trade-proposals"
tags: ["communications"]
---

# Propose Block Trade

`POST /communications/block-trade-proposals`

## Request

- Base URL: `https://external-api.kalshi.com/trade-api/v2`
- URL: `https://external-api.kalshi.com/trade-api/v2/communications/block-trade-proposals`
- Auth: API key in header `KALSHI-ACCESS-KEY` and API key in header `KALSHI-ACCESS-SIGNATURE` and API key in header `KALSHI-ACCESS-TIMESTAMP`

Endpoint for creating a block trade proposal.

## Request body

- ProposeBlockTradeRequest
  - `buyer_user_id` string, required: User ID of the buyer
  - `buyer_subtrader_id` string: Subtrader ID of the buyer. Provide either this or buyer_subaccount, not both.
  - `buyer_subaccount` integer: User-managed subaccount number of the buyer (0 for primary, 1-63 for numbered subaccounts). Provide either this or buyer_subtrader_id, not both.
  - `seller_user_id` string, required: User ID of the seller
  - `seller_subtrader_id` string: Subtrader ID of the seller. Provide either this or seller_subaccount, not both.
  - `seller_subaccount` integer: User-managed subaccount number of the seller (0 for primary, 1-63 for numbered subaccounts). Provide either this or seller_subtrader_id, not both.
  - `market_ticker` string, required: The ticker of the market for this block trade
  - `price_centi_cents` integer, required: Price in centi-cents
  - `centicount` integer, required: Number of contracts in centicounts
  - `maker_side` 'yes' | 'no', required: The maker side of the trade
  - `expiration_ts` string, date-time, required: Expiration time of the proposal

## Response `201`

Block trade proposal created successfully

- ProposeBlockTradeResponse
  - `block_trade_proposal_id` string, required: The ID of the newly created block trade proposal

## Other responses

- `400`: Bad request - invalid input
- `401`: Unauthorized - authentication required
- `403`: Forbidden - insufficient permissions
- `500`: Internal server error

## Changes

- **2026-07-31** `a07481be8bf9`: 4 warning
  - removed the optional property `service` from the response with the `400` status
  - removed the optional property `service` from the response with the `401` status
  - removed the optional property `service` from the response with the `403` status
  - removed the optional property `service` from the response with the `500` status
- **2026-06-17** `5dacc8874900`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/kalshi/apis/kalshi-trade-api-manual-endpoints/changes/communications/block-trade-proposals/post.md)

---

[API](https://skmtc.dev/kalshi/apis/kalshi-trade-api-manual-endpoints.md) - [All operations](https://skmtc.dev/kalshi/apis/kalshi-trade-api-manual-endpoints/llms.txt) - [OpenAPI document](https://skmtc.dev/kalshi/apis/kalshi-trade-api-manual-endpoints/revisions/e6691cdd1915?raw)