Order Entry

Submit, modify, and cancel margin orders through FIX messages

New Order Single (35=D)

Tag	Name	Type	Required	Description
11	ClOrderID	String	Y	Client order identifier for idempotency. UUID format is preferred.
18	ExecInst	Char	N	Execution instruction flags. Supported values: 6 = Post Only, E = Reduce Only (IOC or FOK only)
38	OrderQty	Decimal	Y	Quantity of contracts to trade. Only whole-number quantities are supported.
40	OrdType	Char	Y	Supported values: 2 = Limit
44	Price	Decimal	Y	Price per contract in fixed-point dollars, up to 4 decimal places.
50	SenderSubID	String	N	Clearing FCM sponsored access only. Header field identifying the operator for this order; printable ASCII, max 16 characters.
54	Side	Char	Y	Supported values: 1 = Buy (bid), 2 = Sell (ask)
55	Symbol	String	Y	Market ticker
59	TimeInForce	Char	N	Supported values: 0 = Day, 1 = Good Till Cancel, 3 = Immediate Or Cancel, 4 = Fill Or Kill, 6 = Good Till Date
126	ExpireTime	UTCTimestamp	C	Required when TimeInForce = GTD
448	PartyID	String	N	Only applicable for FCM entities. Customer-account or subaccount identifier.
452	PartyRole	Integer	N	Only applicable for FCM entities. Supported value: 24 = Customer Account
453	NoPartyIDs	Integer	N	Only applicable for FCM entities. Currently only 1 is supported.
79	AllocAccount	Integer	N	Subaccount number (0-63). Alternative to NoPartyIDs.
526	SecondaryClOrdID	UUID	N	Order group identifier.
2964	SelfTradePreventionType	Integer	N	Supported values: 1 = Taker At Cross, 2 = Maker
21006	CancelOrderOnPause	Boolean	N	Cancel the order if trading pauses

SenderSubID<50> is captured on an ordinary NewOrderSingle and, per action, on OrderCancelRequest and OrderCancelReplaceRequest; it is ignored on RFQ quote acceptance. The operator on a NewOrderSingle sticks to the order: fills and other lifecycle reports emit it as the PartyRole=12 party. Cancel and Cancel/Replace acknowledgements instead emit the operator sent on that request — the operator who performed the action — falling back to the order’s creating operator when the request carried none. Do not send tag 50 on Logon: Kalshi rejects that Logon.

Example New Margin Order

8=FIXT.1.1|9=200|35=D|34=5|52=20230809-12:34:56.789|49=your-api-key|56=KalshiNR|
11=550e8400-e29b-41d4-a716-446655440000|38=10.00|40=2|54=1|55=BTC-PERP|44=19.5000|
59=1|10=123|

Order Cancel/Replace Request (35=G)

Used to modify an existing order without canceling it.

Supported Modifications

• OrderQty: Increase or decrease the quantity. Increasing quantity forfeits queue priority.

• Price: Change the limit price.

• Expiry: Use Day (59=0) without 126 to expire at 11:59:59.999pm ET, set a future deadline with TimeInForce=GTD (59=6) and ExpireTime (126), or remove expiry with TimeInForce=GTC (59=1) and no 126. Expired deadlines, including the Unix epoch, are rejected.

Kalshi conventions for replace: Omitting both 59 and 126 preserves the order’s current expiry. This is a Kalshi-specific convention, rather than FIX’s Day default for omitted 59. To resend expiry explicitly, send 59=6 with the unchanged 126 for GTD, 59=0 without 126 for Day, or 59=1 without 126 for GTC. Send the current total OrderQty and price for an expiry-only amendment. Kalshi guarantees that an expiry-only amendment preserves FIFO queue position when price and quantity are unchanged.

Tag	Name	Type	Required	Description
11	ClOrderID	String	Y	Unique modification request identifier
37	OrderID	String	N	Kalshi exchange order identifier
38	OrderQty	Decimal	Y	New total quantity for the order
40	OrdType	Char	Y	Supported value: 2 = Limit
41	OrigClOrdID	String	Y	ClOrderID of the order to modify
44	Price	Decimal	N	New fixed-point dollar price
50	SenderSubID	String	N	Clearing FCM sponsored access only. Header field identifying the operator performing this modification; printable ASCII, max 16 characters.
54	Side	Char	Y	Must match the original order side
55	Symbol	String	Y	Must match the original margin market ticker
59	TimeInForce	Char	N	0=Day sets expiry to 11:59:59.999pm ET and forbids ExpireTime; 1=GTC clears expiry and forbids ExpireTime; 6=GTD requires a future ExpireTime. Omit both tags to preserve expiry (Kalshi convention). Other values are not supported on replace.
126	ExpireTime	UTCTimestamp	C	Future expiration timestamp. Requires TimeInForce=GTD (59=6); cannot be sent alone or with Day/GTC. Expired timestamps, including the Unix epoch, are rejected.
448	PartyID	String	N	FCM customer-account or subaccount identifier
452	PartyRole	Integer	N	FCM party role
453	NoPartyIDs	Integer	N	FCM party count
79	AllocAccount	Integer	N	Subaccount number

Order Cancel Request (35=F)

Cancel all remaining quantity of an existing order.

Tag	Name	Type	Required	Description
11	ClOrderID	String	Y	Unique cancel request identifier
37	OrderID	String	N	Kalshi exchange order identifier
41	OrigClOrdID	String	Y	ClOrderID of the order to cancel
50	SenderSubID	String	N	Clearing FCM sponsored access only. Header field identifying the operator performing this cancel; printable ASCII, max 16 characters.
54	Side	Char	Y	Must match the original order side
55	Symbol	String	Y	Must match the original margin market ticker
448	PartyID	String	N	FCM customer-account or subaccount identifier
452	PartyRole	Integer	N	FCM party role
453	NoPartyIDs	Integer	N	FCM party count
79	AllocAccount	Integer	N	Subaccount number

Execution Report (35=8)

This message is sent by the exchange to reflect changes to an order’s state.

Replaced reports confirm the resulting validity with TimeInForce=GTD (59=6) and the accepted ExpireTime (126), or TimeInForce=GTC (59=1) without 126 when there is no expiry. Kalshi stores Day orders as explicit deadlines, so their Replaced reports also use GTD with the end-of-day ET deadline; they do not echo the original Day value.

Tag	Name	Type	Required	Description
6	AvgPx	Decimal	Y	Average fill price in fixed-point dollars
11	ClOrderID	String	Y	ClOrderID from the last change-making request
14	CumQty	Decimal	Y	Total quantity filled so far
17	ExecID	String	Y	Unique sequenced identifier for this report message
30	LastMkt	String	C	Exchange index that produced the report.
31	LastPx	Decimal	C	Price of the last fill in fixed-point dollars
32	LastQty	Decimal	C	Quantity of the last fill
37	OrderID	String	Y	Exchange order identifier
38	OrderQty	Decimal	Y	Order quantity. By default this is LeavesQty + CumQty; if 21008=Y, it remains the original order quantity.
39	OrdStatus	Char	Y	Current status of the order after this event
41	OrigClOrdID	String	C	Previous ClOrderID for replaced/canceled orders
44	Price	Decimal	C	Limit price in fixed-point dollars
54	Side	Char	Y	Original order side
55	Symbol	String	Y	Margin market ticker
58	Text	String	N	Human-readable result description
59	TimeInForce	Char	C	Present for Replaced reports: 6=GTD when expiry exists (including Day deadlines), otherwise 1=GTC.
60	TransactTime	UTCTimestamp	Y	Timestamp for the triggering event
103	OrdRejReason	Integer	C	Rejection reason when ExecType = Rejected
126	ExpireTime	UTCTimestamp	C	Expiration timestamp
150	ExecType	Char	Y	Why this execution report was sent
151	LeavesQty	Decimal	Y	Remaining quantity open for execution
448	PartyID	String	N	FCM customer-account identifier or the operator captured from SenderSubID
452	PartyRole	Integer	N	FCM party role: 24 = Customer Account, 12 = Executing Trader
453	NoPartyIDs	Integer	N	FCM party count. Up to 2 when both customer account and operator are present.
79	AllocAccount	Integer	C	Subaccount number
715	ClearingBusinessDate	LocalMktDate	C	Clearing date (YYYYMMDD). Each date covers the interval from 4:00 p.m. ET on the prior calendar day (inclusive) to 4:00 p.m. ET on that date (exclusive), including weekends and holidays. Present only for ExecType = Trade

Order Status (39)

• New<0>: Active order, no fills
• Partially Filled<1>: Some quantity filled
• Filled<2>: Completely filled
• Canceled<4>: Canceled
• Replaced<5>: Order modified via Cancel/Replace
• Pending Cancel<6>: Cancel pending
• Rejected<8>: Order rejected
• Pending New<A>: Order pending acceptance
• Expired<C>: Time-in-force expired
• Pending Replace<E>: Modification pending

With default settings, expiry-style system cancellations are reported as Canceled<4>. If 21012 (UseExpiredOrdStatus)=Y, expiry-style system cancellations emit Expired<C>.

Order Rejection Reasons (103)

• Unknown symbol<1>
• Exchange closed<2>
• Order exceeds limit<3>
• Too late to enter<4>
• Stale order<5>
• Duplicate order<6>
• Unsupported order characteristic<11>
• Incorrect quantity<13>
• Unknown account<15>
• Other<99>

Execution Types (150)

• New<0>
• Trade<F>
• Canceled<4>
• Replaced<5>
• Rejected<8>
• Expired<C>
• Pending New<A>
• Pending Cancel<6>
• Pending Replace<E>

Text Field Values (58)

Common values include:

• EXCHANGE_UNAVAILABLE
• INTERNAL_ERROR
• MARKET_ALREADY_CLOSED
• MARKET_INACTIVE
• MARKET_NOT_FOUND
• SELF_CROSS_ATTEMPT
• ORDER_ALREADY_EXISTS
• EXCEEDED_PER_MARKET_RISK_LIMIT
• EXCEEDED_ORDER_GROUP_RISK_LIMIT
• ORDER_GROUP_NOT_FOUND
• FOK_INSUFFICIENT_VOLUME
• POST_ONLY_CROSS
• ORDER_GROUP_CANCEL
• TAKER_CANCEL_FOR_SELF_TRADE_PREVENTION
• MAKER_CANCEL_FOR_SELF_TRADE_PREVENTION
• IMMEDIATE_OR_CANCELLED
• REDUCE_ONLY

OrderCancelReject (35=9)

Exchange-returned amend and cancel failures are returned as OrderCancelReject (35=9), not ExecutionReport.

Text (58)	CxlRejReason (102)
INVALID_AMEND_QTY_FOR_ORDER	Broker
CANNOT_UPDATE_FILLED_ORDER	Broker
SELF_CROSS_ATTEMPT	Invalid price increment

Position and Fee Information

When ExecType = Trade:

Tag	Name	Description
704	LongQty	Net long position after trade
705	ShortQty	Net short position after trade
136	NoMiscFees	Number of fees
137	MiscFeeAmt	Total fees in dollars
138	MiscFeeCurr	Currency (USD)
139	MiscFeeType	Exchange fees
891	MiscFeeBasis	Fee unit (always ABSOLUTE<0>)
880	TrdMatchID	Trade identifier
1057	AggressorIndicator	Taker/maker flag

Collateral Changes

Tag	Name	Description
1703	NoCollateralAmountChanges	Number of collateral changes
1704	CollateralAmountChange	Delta in dollars
1705	CollateralAmountType	Balance or payout

Party Information

Execution reports independently include the customer account when applicable and at most one operator entry (Executing Trader<12>). Which operator appears depends on the report type: fills and other order-lifecycle reports (expiration, IOC cancellation, and similar) carry the operator captured at order creation, while Cancel and Cancel/Replace acknowledgements carry the operator sent on the acting request, falling back to the creation operator when that request carried none. When both a customer-account entry and an operator entry are present, the customer-account entry comes first.

Tag	Name	Description
453	NoPartyIDs	Number of parties: one or two
448	PartyID	Customer-account or operator identifier
452	PartyRole	Customer Account<24> or Executing Trader<12>
79	AllocAccount	Subaccount number (0-63)

Rejection Reasons (102)

• Too late to cancel<0>
• Unknown order<1>
• Other<99>

Mass Cancel Request (35=q)

Cancel resting orders in bulk. Only available on KalshiNR (NewOrderMode) sessions. 530=6 cancels every resting order placed over FIX with the session’s API key. 530=1 cancels every resting order the account has in the market named by Symbol<55>, both sides, however it was placed, or only one subaccount’s when the request names it; it is billed like an order cancel (35=F).

Tag	Name	Description
11	ClOrderID	Unique request ID
530	MassCancelRequestType	Cancel for session<6> or Cancel orders for a security<1>
55	Symbol	Market ticker. Required when 530=1.
448	PartyID	Only applicable for FCM entities. Customer-account identifier. With 530=1, cancels only that customer account’s orders in the market.
452	PartyRole	Only applicable for FCM entities. Supported value: 24 = Customer Account
453	NoPartyIDs	Only applicable for FCM entities. Currently only 1 is supported.
79	AllocAccount	Subaccount number (0-63). With 530=1, cancels only that subaccount’s orders in the market; omit to cancel across all subaccounts. Not used with 530=6.

Mass Cancel Report (35=r)

Response to mass cancel request.

Tag	Name	Description
11	ClOrderID	Request ID
37	OrderID	Operation ID
55	Symbol	Market ticker, echoed when 530=1
531	MassCancelResponse	Cancel orders for a security<1>, Cancel for session<6>, or Rejected<0>
532	MassCancelRejectReason	If rejected: Invalid or unknown security<1> or Other<99>

The report acknowledges the request. Individual ExecutionReports follow for each cancelled order.

Corporate actions: SecurityStatus (35=f)

Every KalshiNR and KalshiRT session, including listener sessions, receives a SecurityStatus (35=f) when the exchange applies a stock split, final settlement or ticker change to any margin market. No request is needed, and cash corporate actions are not sent. Each message follows that market’s earlier execution reports. KalshiRT retains these messages for retransmission like its other messages; KalshiNR sends nothing missed while disconnected, and KalshiMD sessions do not receive them. An applied corporate action can change positions and balances without a fill. Use GET /trade-api/v2/margin/corporate_actions for upcoming and recent notices, including cash actions.

Every event carries CorporateActionNoticeID<20190>, the id of the matching notice in GET /trade-api/v2/margin/corporate_actions. TransactTime<60> is when the exchange applied the action. Money fields are in dollars.

Tag	Name	Type	Presence	Description
55	Symbol	String	Always	Margin market ticker; the new ticker for a ticker change.
325	UnsolicitedIndicator	Boolean	Always	Y.
20190	CorporateActionNoticeID	String	Always	Notice ID.
60	TransactTime	UTCTimestamp	Always	Exchange timestamp, in UTC with microsecond precision.
58	Text	String	Always	Human-readable action; the split ratio or old and new tickers where applicable.
292	CorporateAction	MultipleCharValue	Splits and ticker changes	Action code in the table below.
1174	SecurityTradingEvent	Int	Always	9=CorporateAction, indicating that the action occurred.
730	SettlementPrice	Price	Final settlement	Settlement price per contract.
731	SettlementPriceType	Int	With 730	1=Final.

Action	CorporateAction (292)
Forward split with integer new/old ratio	J=StandardIntegerStockSplit
Forward split with non-integer new/old ratio	H=NonIntegerStockSplit
Reverse split (new ratio less than old ratio)	I=ReverseStockSplit
Ticker change	T=SymbolConversion
Final settlement	Omitted; the reason is on the REST notice

Example applied split

8=FIXT.1.1|35=f|49=KalshiNR|56=your-api-key|55=KXMUPERP1|58=Corporate action review-uuid: split 1 to 4|60=20261013-20:00:01.123456|292=J|325=Y|1174=9|20190=review-uuid|

The message model follows FIX Latest Pre-Trade EP284 sections 8.1.13 and 19.1.10. The action codes follow the FIX Latest CorporateAction code set. Security master messages 35=c, 35=d, and 35=BP are not used; splits do not change contract terms.