Commission (FIX tag 12)

AmtFIX 4.4FIX 4.2FIX 5.0 SP2

Commission (tag 12) is an Amt field defined in FIX 4.4, FIX 4.2 and FIX 5.0 SP2. It appears in 16 message types, always optionally.

At a glance

Tag: 12
Name: Commission
Datatype: Amt (float)
Dialects: FIX 4.4, FIX 4.2 and FIX 5.0 SP2
Messages: 16

What the specification says

FIX 4.4

Commission. Note if CommType (3) is percentage, Commission of 5% should be represented as .05.

FIX 4.2

Commission. Note if CommType is percentage, Commission of 5% should be represented as .05.

FIX 5.0 SP2

Commission. Note if CommType (13) is percentage, Commission of 5% should be represented as .05.

Descriptions are quoted from the FIX Orchestra sources under the Apache 2.0 licence.

A real message using tag 12

NewOrderSingle · FIX 4.4

Tag	Field	Wire value	Meaning
8	BeginString	FIX.4.4
9	BodyLength	124
35	MsgType	D	Order – Single
49	SenderCompID	BOARTEAM
56	TargetCompID	COUNTERPARTY
34	MsgSeqNum	2
52	SendingTime	20240101-12:00:00.000
11	ClOrdID	ORD-10042
54	Side	1	Buy
60	TransactTime	20240101-12:00:00.000
40	OrdType	1	Market
12	Commission	125000.00
10	CheckSum	075

Edit and decode it yourself

Shown with | separators for readability. On the wire FIX uses SOH (0x01), an invisible control byte — and because BodyLength and CheckSum are computed over the actual bytes, the two forms have different checksums. Both are valid and both decode here.

Open in the full decoder →

Generated from the FIX 4.4 dictionary and verified at build time: it parses and validates with no issues. Open the decoder to try your own message.

Where tag 12 appears

Requiredness is a property of the message, not of the field: the same tag can be optional in one message and conditionally required in another.

Message	MsgType	FIX 4.4	FIX 4.2	FIX 5.0 SP2	Where in the message
AllocationInstruction	J	Optional	Optional	Optional	inside AllocGrp › CommissionData
AllocationInstructionAlert	BM	—	—	Optional	inside AllocGrp › CommissionData
AllocationReport	AS	Optional	—	Optional	inside AllocGrp › CommissionData
BidResponse	l	Optional	Required	Optional	inside BidCompRspGrp › CommissionData
Confirmation	AK	Optional	—	Optional	inside the CommissionData component
CrossOrderCancelReplaceRequest	t	Optional	—	Optional	inside SideCrossOrdModGrp › CommissionData
ExecutionReport	8	Optional	Optional	Optional	inside the CommissionData component
MultilegOrderCancelReplace	AC	Optional	—	Optional	inside the CommissionData component
NewOrderCross	s	Optional	—	Optional	inside SideCrossOrdModGrp › CommissionData
NewOrderList	E	Optional	Optional	Optional	inside ListOrdGrp › CommissionData
NewOrderMultileg	AB	Optional	—	Optional	inside the CommissionData component
NewOrderSingle	D	Optional	Optional	Optional	inside the CommissionData component
OrderCancelReplaceRequest	G	Optional	Optional	Optional	inside the CommissionData component
Quote	S	Optional	—	Optional	directly on the message body
QuoteResponse	AJ	Optional	—	Optional	directly on the message body
QuoteStatusReport	AI	Optional	—	Optional	directly on the message body
TradeCaptureReport	AE	Optional	—	Optional	inside TrdCapRptSideGrp › CommissionData
TradeCaptureReportAck	AR	—	—	Optional	inside TrdCapRptAckSideGrp › CommissionData

Wire format

A decimal monetary amount, in the currency named by the message's currency field. @boarteam/fix parses the value as a number and reports parse/invalid-float when it does not lex as one; the raw string is kept so precision and trailing zeros are never lost.

Read tag 12 in TypeScript

decode.tsts

import { createFixEngine } from "@boarteam/fix";import { dictionary } from "@boarteam/fix-dict-fix44";const fix = createFixEngine(dictionary);const { message, issues } = fix.parse(raw);const field = message.fields[12];field?.name;   // "Commission"field?.raw;    // the verbatim wire stringfield?.value;  // coerced to a number

Decode this in your own code

The same engine that produced the decoded example above is an Apache-2.0 npm package with zero runtime dependencies. It runs in Node and in the browser, and parse() returns problems as data instead of throwing.

npm i @boarteam/fix @boarteam/fix-dict-fix44

Try the decoder Source on GitHub