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Documentation Index

Fetch the complete documentation index at: https://docs.kalshi.com/llms.txt

Use this file to discover all available pages before exploring further.

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FIX API Changelog

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Version 1.0.25 (2026-05-08)

BidSize (134) and OfferSize (135) conditionally offered on QuoteStatusReport (35=AI).

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Version 1.0.24 (2026-05-07)

  • OrderGroupResponse (UOH) now echoes AllocAccount (tag 79), with 79=0 for the primary account and 79=1-32 for subaccounts

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Version 1.0.23 (2026-05-05)

  • Quote (35=S) now accepts RestRemainder (21015)
    • Set 21015=Y to rest the quote remainder after execution
    • Omitting the tag or setting 21015=N preserves the existing behavior

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Version 1.0.22 (2026-04-28)

  • Added AlwaysEmitNewBeforeTrade (21026) Logon flag
    • With Logon flag 21026=Y, the gateway always emits a standalone New<0> execution report before any Trade<F> report, even when an order takes liquidity in the same matching cycle as its placement
    • Without 21026, the New ack continues to be folded into the first Trade report when both events arrive in the same batch (existing behavior)
    • Useful for clients whose state machines require an explicit 39=0 ack before they can issue replaces against the order

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Version 1.0.21 (2026-04-20)

  • OrderGroupRequest (UOG) now accepts AllocAccount (tag 79) to scope the operation to a subaccount
    • Applies to all five actions: Create, Reset, Delete, Trigger, Update
    • Omit or set 79=0 to operate on the primary account
    • An OrderGroupID created under one subaccount cannot be managed without the matching AllocAccount on the follow-up request
  • OrderGroupResponse (UOH) now echoes OrderGroupContractsLimit (tag 20132) on Create and Update responses

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Version 1.0.20 (2026-03-01)

  • Added OrderExpiryCancel support for expired status mapping in execution reports
    • With Logon flag 21012=Y, both CloseCancel and OrderExpiryCancel emit ExecType(150)=C and OrdStatus(39)=C
    • Without 21012, behavior remains Canceled<4> for compatibility

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Version 1.0.19 (2026-02-27)

  • SettlementPrice (730) precision extended in MarketSettlementReport
    • SettlementPrice will continue to be in cents but may have up to two decimal places (e.g. 30.60 instead of 30)
    • This enables sub-cent settlement values to be represented without truncation
  • MiscFeeAmt (137) now reports actual settlement fees in MarketSettlementReport
    • Previously hardcoded to zero; now reflects the real settlement fee for each position

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Version 1.0.18 (2026-02-12)

  • Execution report precision extended for fractional shares
    • On qty fields, Kalshi will return at least a scale of 2 instead of 0.
    • E.g. on a trade which executes for 10 contracts, Kalshi will return CumQty: 14=10.00 as opposed to 14=10
    • Despite the change in precision, the numerical value will remain unchanged for now because fractional trading is not yet enabled on any market.
    • Affected fields: LastQty, CumQty, LeavesQty

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Version 1.0.17 (2025-11-30)

  • BREAKING CHANGE: Tag reorganization for improved compatibility
    • QuoteConfirmStatus now uses tag 21010 (currently supporting both 297 and 21010)
    • SkipPendingExecReports now uses tag 21011 (currently accepting both 21003 and 21011)
    • Tag 297 designated for standard QuoteStatus field
    • Tag 21003 designated for ResendEventCount field
    • Clients should update to use new tags; legacy support will be removed in future version

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Version 1.0.16 (2025-11-30)

  • Added MaxExecutionCost (21009) NewOrderSingle flag.

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Version 1.0.15 (2025-11-21)

  • Added PreserveOriginalOrderQty (21008) Logon flag to maintain original OrderQty across all execution reports

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Version 1.0.14 (2025-10-01)

  • Added support for subpenny pricing across multiple FIX messages
  • For more info see Subpenny Pricing

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Version 1.0.13 (2025-08-15)

  • Added Order Group management messages (UOG/UOH)
  • Support for automatic order cancellation with contracts limits
  • Create, Reset, and Delete operations for order groups

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Version 1.0.12 (2025-06-26)

  • Added support for ListenerSession Logon flag for KalshiNR/KalshiRT
  • Added support for ReceiveSettlementReports Logon flag for KalshiRT
  • Deprecated SecurityGroup

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Version 1.0.11 (2025-06-12)

  • Removed Required from OrderQty on Cancel 35=F
  • Added PostOnly to Create 35=D

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Version 1.0.10 (2025-04-15)

  • Removed deprecated event settlement message type
  • Added ListenerSession and SkipPendingExecReports flag to Logon message type