diff --git a/packages/codegen.go/src/operations.ts b/packages/codegen.go/src/operations.ts
index 1c0abd244..a8bb93f98 100644
--- a/packages/codegen.go/src/operations.ts
+++ b/packages/codegen.go/src/operations.ts
@@ -736,12 +736,21 @@ function createProtocolRequest(azureARM: boolean, client: go.Client, method: go.
       headerParams.push(param);
     }
   }
+
+  let contentType: string | undefined;
   for (const param of headerParams.sort((a: go.HeaderParameter, b: go.HeaderParameter) => { return helpers.sortAscending(a.headerName, b.headerName);})) {
     if (param.headerName.match(/^content-type$/)) {
       // canonicalize content-type as req.SetBody checks for it via its canonicalized name :(
       param.headerName = 'Content-Type';
     }
-    if (go.isRequiredParameter(param) || go.isLiteralParameter(param) || go.isClientSideDefault(param.kind)) {
+
+    if (param.headerName === 'Content-Type' && param.kind === 'literal') {
+      // the content-type header will be set as part of emitSetBodyWithErrCheck
+      // to handle cases where the body param is optional. we don't want to set
+      // the content-type if the body is nil.
+      // we do it like this as tsp specifies content-type while swagger does not.
+      contentType = helpers.formatParamValue(param, imports);
+    } else if (go.isRequiredParameter(param) || go.isLiteralParameter(param) || go.isClientSideDefault(param.kind)) {
       text += emitHeaderSet(param, '\t');
     } else if (param.location === 'client' && !param.group) {
       // global optional param
@@ -757,8 +766,12 @@ function createProtocolRequest(azureARM: boolean, client: go.Client, method: go.
 
   const partialBodyParams = values(method.parameters).where((param: go.Parameter) => { return go.isPartialBodyParameter(param); }).toArray();
   const bodyParam = <go.BodyParameter | undefined>values(method.parameters).where((each: go.Parameter) => { return go.isBodyParameter(each) || go.isFormBodyParameter(each) || go.isMultipartFormBodyParameter(each); }).first();
-  const emitSetBodyWithErrCheck = function(setBodyParam: string): string {
-    return `if err := ${setBodyParam}; err != nil {\n\treturn nil, err\n}\n`;
+  const emitSetBodyWithErrCheck = function(setBodyParam: string, contentType?: string): string {
+    let content = `if err := ${setBodyParam}; err != nil {\n\treturn nil, err\n}\n;`;
+    if (contentType) {
+      content = `req.Raw().Header["Content-Type"] = []string{${contentType}}\n` + content;
+    }
+    return content;
   };
 
   if (partialBodyParams.length > 0) {
@@ -783,6 +796,8 @@ function createProtocolRequest(azureARM: boolean, client: go.Client, method: go.
         text += `\t\tbody.${capitalize(partialBodyParam.serializedName)} = options.${capitalize(partialBodyParam.name)}\n\t}\n`;
       }
     }
+    // TODO: spread params are JSON only https://github.com/Azure/autorest.go/issues/1455
+    text += '\treq.Raw().Header["Content-Type"] = []string{"application/json"}\n';
     text += '\tif err := runtime.MarshalAsJSON(req, body); err != nil {\n\t\treturn nil, err\n\t}\n';
     text += '\treturn req, nil\n';
   } else if (!bodyParam) {
@@ -844,22 +859,22 @@ function createProtocolRequest(azureARM: boolean, client: go.Client, method: go.
       setBody = `req.SetBody(streaming.NopCloser(bytes.NewReader(${body})), "application/${bodyParam.bodyFormat.toLowerCase()}")`;
     }
     if (go.isRequiredParameter(bodyParam) || go.isLiteralParameter(bodyParam)) {
-      text += `\t${emitSetBodyWithErrCheck(setBody)}`;
+      text += `\t${emitSetBodyWithErrCheck(setBody, contentType)}`;
       text += '\treturn req, nil\n';
     } else {
       text += emitParamGroupCheck(bodyParam);
-      text += `\t${emitSetBodyWithErrCheck(setBody)}`;
+      text += `\t${emitSetBodyWithErrCheck(setBody, contentType)}`;
       text += '\t\treturn req, nil\n';
       text += '\t}\n';
       text += '\treturn req, nil\n';
     }
   } else if (bodyParam.bodyFormat === 'binary') {
     if (go.isRequiredParameter(bodyParam)) {
-      text += `\t${emitSetBodyWithErrCheck(`req.SetBody(${bodyParam.name}, ${bodyParam.contentType})`)}`;
+      text += `\t${emitSetBodyWithErrCheck(`req.SetBody(${bodyParam.name}, ${bodyParam.contentType})`, contentType)}`;
       text += '\treturn req, nil\n';
     } else {
       text += emitParamGroupCheck(bodyParam);
-      text += `\t${emitSetBodyWithErrCheck(`req.SetBody(${helpers.getParamName(bodyParam)}, ${bodyParam.contentType})`)}`;
+      text += `\t${emitSetBodyWithErrCheck(`req.SetBody(${helpers.getParamName(bodyParam)}, ${bodyParam.contentType})`, contentType)}`;
       text += '\treturn req, nil\n';
       text += '\t}\n';
       text += '\treturn req, nil\n';
@@ -870,12 +885,12 @@ function createProtocolRequest(azureARM: boolean, client: go.Client, method: go.
     const bodyParam = <go.BodyParameter>values(method.parameters).where((each: go.Parameter) => { return go.isBodyParameter(each); }).first();
     if (go.isRequiredParameter(bodyParam)) {
       text += `\tbody := streaming.NopCloser(strings.NewReader(${bodyParam.name}))\n`;
-      text += `\t${emitSetBodyWithErrCheck(`req.SetBody(body, ${bodyParam.contentType})`)}`;
+      text += `\t${emitSetBodyWithErrCheck(`req.SetBody(body, ${bodyParam.contentType})`, contentType)}`;
       text += '\treturn req, nil\n';
     } else {
       text += emitParamGroupCheck(bodyParam);
       text += `\tbody := streaming.NopCloser(strings.NewReader(${helpers.getParamName(bodyParam)}))\n`;
-      text += `\t${emitSetBodyWithErrCheck(`req.SetBody(body, ${bodyParam.contentType})`)}`;
+      text += `\t${emitSetBodyWithErrCheck(`req.SetBody(body, ${bodyParam.contentType})`, contentType)}`;
       text += '\treturn req, nil\n';
       text += '\t}\n';
       text += '\treturn req, nil\n';
diff --git a/packages/typespec-go/CHANGELOG.md b/packages/typespec-go/CHANGELOG.md
index 6bc7efa0f..b0624d3c7 100644
--- a/packages/typespec-go/CHANGELOG.md
+++ b/packages/typespec-go/CHANGELOG.md
@@ -10,6 +10,7 @@
 
 * Fake servers will honor the caller's context in the `*http.Request`.
 * Add missing error check when parsing multipart/form content in fakes.
+* Optional request bodies will only set the `Content-Type` header when a body is specified.
 
 ### Other Fixes
 
diff --git a/packages/typespec-go/src/tcgcadapter/clients.ts b/packages/typespec-go/src/tcgcadapter/clients.ts
index d9ed573f2..d7b4ee47a 100644
--- a/packages/typespec-go/src/tcgcadapter/clients.ts
+++ b/packages/typespec-go/src/tcgcadapter/clients.ts
@@ -324,6 +324,15 @@ export class clientAdapter {
         throw new Error(`didn't find operation parameter for method ${sdkMethod.name} parameter ${param.name}`);
       }
 
+      if (opParam.kind === 'header' && opParam.serializedName.match(/^content-type$/i) && param.type.kind === 'constant') {
+        // if the body param is optional, then the content-type param is also optional.
+        // for optional constants, this has the side effect of the param being treated like
+        // a flag which isn't what we want. so, we mark it as required. we ONLY do this
+        // if the content-type is a constant (i.e. literal value).
+        // the content-type will be conditionally set based on the requiredness of the body.
+        opParam.optional = false;
+      }
+
       let adaptedParam: go.Parameter;
       if (opParam.kind === 'body' && opParam.type.kind === 'model' && opParam.type.kind !== param.type.kind) {
         const paramKind = this.adaptParameterKind(param);
@@ -687,7 +696,6 @@ export class clientAdapter {
   private adaptParameterKind(param: tcgc.SdkBodyParameter | tcgc.SdkEndpointParameter | tcgc.SdkHeaderParameter | tcgc.SdkMethodParameter | tcgc.SdkPathParameter | tcgc.SdkQueryParameter): go.ParameterKind {
     // NOTE: must check for constant type first as it will also set clientDefaultValue
     if (param.type.kind === 'constant') {
-      // TODO: https://github.com/Azure/autorest.go/issues/1444
       if (param.optional) {
         return 'flag';
       }
diff --git a/packages/typespec-go/test/armlargeinstance/fake/zz_azurelargeinstance_server.go b/packages/typespec-go/test/armlargeinstance/fake/zz_azurelargeinstance_server.go
index aa937a2b2..b633c7343 100644
--- a/packages/typespec-go/test/armlargeinstance/fake/zz_azurelargeinstance_server.go
+++ b/packages/typespec-go/test/armlargeinstance/fake/zz_azurelargeinstance_server.go
@@ -334,12 +334,10 @@ func (a *AzureLargeInstanceServerTransport) dispatchBeginRestart(req *http.Reque
 		if err != nil {
 			return nil, err
 		}
-		contentTypeParam := getOptional(getHeaderValue(req.Header, "Content-Type"))
 		var options *armlargeinstance.AzureLargeInstanceClientBeginRestartOptions
-		if !reflect.ValueOf(body).IsZero() || contentTypeParam != nil {
+		if !reflect.ValueOf(body).IsZero() {
 			options = &armlargeinstance.AzureLargeInstanceClientBeginRestartOptions{
 				ForceParameter: &body,
-				ContentType:    contentTypeParam,
 			}
 		}
 		respr, errRespr := a.srv.BeginRestart(req.Context(), resourceGroupNameParam, azureLargeInstanceNameParam, options)
diff --git a/packages/typespec-go/test/armlargeinstance/fake/zz_internal.go b/packages/typespec-go/test/armlargeinstance/fake/zz_internal.go
index 9989d5e3c..7425b6a66 100644
--- a/packages/typespec-go/test/armlargeinstance/fake/zz_internal.go
+++ b/packages/typespec-go/test/armlargeinstance/fake/zz_internal.go
@@ -7,7 +7,6 @@ package fake
 import (
 	"github.com/Azure/azure-sdk-for-go/sdk/azcore/fake/server"
 	"net/http"
-	"reflect"
 	"sync"
 )
 
@@ -33,21 +32,6 @@ func contains[T comparable](s []T, v T) bool {
 	return false
 }
 
-func getHeaderValue(h http.Header, k string) string {
-	v := h[k]
-	if len(v) == 0 {
-		return ""
-	}
-	return v[0]
-}
-
-func getOptional[T any](v T) *T {
-	if reflect.ValueOf(v).IsZero() {
-		return nil
-	}
-	return &v
-}
-
 func newTracker[T any]() *tracker[T] {
 	return &tracker[T]{
 		items: map[string]*T{},
diff --git a/packages/typespec-go/test/armlargeinstance/zz_azurelargeinstance_client.go b/packages/typespec-go/test/armlargeinstance/zz_azurelargeinstance_client.go
index d7a55b514..dd4e5055e 100644
--- a/packages/typespec-go/test/armlargeinstance/zz_azurelargeinstance_client.go
+++ b/packages/typespec-go/test/armlargeinstance/zz_azurelargeinstance_client.go
@@ -421,10 +421,8 @@ func (client *AzureLargeInstanceClient) restartCreateRequest(ctx context.Context
 	reqQP.Set("api-version", "2024-08-01-preview")
 	req.Raw().URL.RawQuery = reqQP.Encode()
 	req.Raw().Header["Accept"] = []string{"application/json"}
-	if options != nil && options.ContentType != nil {
-		req.Raw().Header["Content-Type"] = []string{"application/json"}
-	}
 	if options != nil && options.ForceParameter != nil {
+		req.Raw().Header["Content-Type"] = []string{"application/json"}
 		if err := runtime.MarshalAsJSON(req, *options.ForceParameter); err != nil {
 			return nil, err
 		}
diff --git a/packages/typespec-go/test/armlargeinstance/zz_options.go b/packages/typespec-go/test/armlargeinstance/zz_options.go
index 4b7f75777..d46dea146 100644
--- a/packages/typespec-go/test/armlargeinstance/zz_options.go
+++ b/packages/typespec-go/test/armlargeinstance/zz_options.go
@@ -10,9 +10,6 @@ type AzureLargeInstanceClientBeginRestartOptions struct {
 	// Resumes the long-running operation from the provided token.
 	ResumeToken string
 
-	// Body parameter's content type. Known values are application/json
-	ContentType *string
-
 	// When set to 'active', this parameter empowers the server with the ability to forcefully terminate and halt any existing
 	// processes that may be running on the server
 	ForceParameter *ForceState
diff --git a/packages/typespec-go/test/cadlranch/parameters/basicparamsgroup/zz_basicimplicitbody_client.go b/packages/typespec-go/test/cadlranch/parameters/basicparamsgroup/zz_basicimplicitbody_client.go
index ca0e15328..0da1b929f 100644
--- a/packages/typespec-go/test/cadlranch/parameters/basicparamsgroup/zz_basicimplicitbody_client.go
+++ b/packages/typespec-go/test/cadlranch/parameters/basicparamsgroup/zz_basicimplicitbody_client.go
@@ -50,12 +50,12 @@ func (client *BasicImplicitBodyClient) simpleCreateRequest(ctx context.Context,
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	body := struct {
 		Name string `json:"name"`
 	}{
 		Name: name,
 	}
+	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	if err := runtime.MarshalAsJSON(req, body); err != nil {
 		return nil, err
 	}
diff --git a/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/fake/zz_bodyoptionalityoptionalexplicit_server.go b/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/fake/zz_bodyoptionalityoptionalexplicit_server.go
index 0387c600a..24e89b3e8 100644
--- a/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/fake/zz_bodyoptionalityoptionalexplicit_server.go
+++ b/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/fake/zz_bodyoptionalityoptionalexplicit_server.go
@@ -88,12 +88,10 @@ func (b *BodyOptionalityOptionalExplicitServerTransport) dispatchOmit(req *http.
 	if err != nil {
 		return nil, err
 	}
-	contentTypeParam := getOptional(getHeaderValue(req.Header, "Content-Type"))
 	var options *bodyoptionalgroup.BodyOptionalityOptionalExplicitClientOmitOptions
-	if !reflect.ValueOf(body).IsZero() || contentTypeParam != nil {
+	if !reflect.ValueOf(body).IsZero() {
 		options = &bodyoptionalgroup.BodyOptionalityOptionalExplicitClientOmitOptions{
-			Body:        &body,
-			ContentType: contentTypeParam,
+			Body: &body,
 		}
 	}
 	respr, errRespr := b.srv.Omit(req.Context(), options)
@@ -119,12 +117,10 @@ func (b *BodyOptionalityOptionalExplicitServerTransport) dispatchSet(req *http.R
 	if err != nil {
 		return nil, err
 	}
-	contentTypeParam := getOptional(getHeaderValue(req.Header, "Content-Type"))
 	var options *bodyoptionalgroup.BodyOptionalityOptionalExplicitClientSetOptions
-	if !reflect.ValueOf(body).IsZero() || contentTypeParam != nil {
+	if !reflect.ValueOf(body).IsZero() {
 		options = &bodyoptionalgroup.BodyOptionalityOptionalExplicitClientSetOptions{
-			Body:        &body,
-			ContentType: contentTypeParam,
+			Body: &body,
 		}
 	}
 	respr, errRespr := b.srv.Set(req.Context(), options)
diff --git a/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/fake/zz_internal.go b/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/fake/zz_internal.go
index b90cb5adf..edd9ca564 100644
--- a/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/fake/zz_internal.go
+++ b/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/fake/zz_internal.go
@@ -6,7 +6,6 @@ package fake
 
 import (
 	"net/http"
-	"reflect"
 	"sync"
 )
 
@@ -32,21 +31,6 @@ func contains[T comparable](s []T, v T) bool {
 	return false
 }
 
-func getHeaderValue(h http.Header, k string) string {
-	v := h[k]
-	if len(v) == 0 {
-		return ""
-	}
-	return v[0]
-}
-
-func getOptional[T any](v T) *T {
-	if reflect.ValueOf(v).IsZero() {
-		return nil
-	}
-	return &v
-}
-
 func initServer[T any](mu *sync.Mutex, dst **T, src func() *T) {
 	mu.Lock()
 	if *dst == nil {
diff --git a/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_bodyoptionality_client.go b/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_bodyoptionality_client.go
index a5765ded0..5d5b63bc2 100644
--- a/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_bodyoptionality_client.go
+++ b/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_bodyoptionality_client.go
@@ -96,12 +96,12 @@ func (client *BodyOptionalityClient) requiredImplicitCreateRequest(ctx context.C
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	body := struct {
 		Name string `json:"name"`
 	}{
 		Name: name,
 	}
+	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	if err := runtime.MarshalAsJSON(req, body); err != nil {
 		return nil, err
 	}
diff --git a/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_bodyoptionalityoptionalexplicit_client.go b/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_bodyoptionalityoptionalexplicit_client.go
index 80fa774e5..4b4b31951 100644
--- a/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_bodyoptionalityoptionalexplicit_client.go
+++ b/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_bodyoptionalityoptionalexplicit_client.go
@@ -50,10 +50,8 @@ func (client *BodyOptionalityOptionalExplicitClient) omitCreateRequest(ctx conte
 	if err != nil {
 		return nil, err
 	}
-	if options != nil && options.ContentType != nil {
-		req.Raw().Header["Content-Type"] = []string{"application/json"}
-	}
 	if options != nil && options.Body != nil {
+		req.Raw().Header["Content-Type"] = []string{"application/json"}
 		if err := runtime.MarshalAsJSON(req, *options.Body); err != nil {
 			return nil, err
 		}
@@ -94,10 +92,8 @@ func (client *BodyOptionalityOptionalExplicitClient) setCreateRequest(ctx contex
 	if err != nil {
 		return nil, err
 	}
-	if options != nil && options.ContentType != nil {
-		req.Raw().Header["Content-Type"] = []string{"application/json"}
-	}
 	if options != nil && options.Body != nil {
+		req.Raw().Header["Content-Type"] = []string{"application/json"}
 		if err := runtime.MarshalAsJSON(req, *options.Body); err != nil {
 			return nil, err
 		}
diff --git a/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_options.go b/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_options.go
index eb634abed..19e1fef07 100644
--- a/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_options.go
+++ b/packages/typespec-go/test/cadlranch/parameters/bodyoptionalgroup/zz_options.go
@@ -20,16 +20,10 @@ type BodyOptionalityClientRequiredImplicitOptions struct {
 // method.
 type BodyOptionalityOptionalExplicitClientOmitOptions struct {
 	Body *BodyModel
-
-	// Body parameter's content type. Known values are application/json
-	ContentType *string
 }
 
 // BodyOptionalityOptionalExplicitClientSetOptions contains the optional parameters for the BodyOptionalityOptionalExplicitClient.Set
 // method.
 type BodyOptionalityOptionalExplicitClientSetOptions struct {
 	Body *BodyModel
-
-	// Body parameter's content type. Known values are application/json
-	ContentType *string
 }
diff --git a/packages/typespec-go/test/cadlranch/parameters/spreadgroup/zz_spreadalias_client.go b/packages/typespec-go/test/cadlranch/parameters/spreadgroup/zz_spreadalias_client.go
index 720056831..1c53ced84 100644
--- a/packages/typespec-go/test/cadlranch/parameters/spreadgroup/zz_spreadalias_client.go
+++ b/packages/typespec-go/test/cadlranch/parameters/spreadgroup/zz_spreadalias_client.go
@@ -53,12 +53,12 @@ func (client *SpreadAliasClient) spreadAsRequestBodyCreateRequest(ctx context.Co
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	body := struct {
 		Name string `json:"name"`
 	}{
 		Name: name,
 	}
+	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	if err := runtime.MarshalAsJSON(req, body); err != nil {
 		return nil, err
 	}
@@ -101,13 +101,13 @@ func (client *SpreadAliasClient) spreadAsRequestParameterCreateRequest(ctx conte
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	req.Raw().Header["x-ms-test-header"] = []string{xMSTestHeader}
 	body := struct {
 		Name string `json:"name"`
 	}{
 		Name: name,
 	}
+	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	if err := runtime.MarshalAsJSON(req, body); err != nil {
 		return nil, err
 	}
@@ -152,7 +152,6 @@ func (client *SpreadAliasClient) spreadParameterWithInnerAliasCreateRequest(ctx
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	req.Raw().Header["x-ms-test-header"] = []string{xMSTestHeader}
 	body := struct {
 		Name string `json:"name"`
@@ -161,6 +160,7 @@ func (client *SpreadAliasClient) spreadParameterWithInnerAliasCreateRequest(ctx
 		Name: name,
 		Age:  age,
 	}
+	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	if err := runtime.MarshalAsJSON(req, body); err != nil {
 		return nil, err
 	}
@@ -203,13 +203,13 @@ func (client *SpreadAliasClient) spreadParameterWithInnerModelCreateRequest(ctx
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	req.Raw().Header["x-ms-test-header"] = []string{xMSTestHeader}
 	body := struct {
 		Name string `json:"name"`
 	}{
 		Name: name,
 	}
+	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	if err := runtime.MarshalAsJSON(req, body); err != nil {
 		return nil, err
 	}
@@ -254,7 +254,6 @@ func (client *SpreadAliasClient) spreadWithMultipleParametersCreateRequest(ctx c
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	req.Raw().Header["x-ms-test-header"] = []string{xMSTestHeader}
 	body := struct {
 		RequiredString     string   `json:"requiredString"`
@@ -271,6 +270,7 @@ func (client *SpreadAliasClient) spreadWithMultipleParametersCreateRequest(ctx c
 	if options != nil && options.OptionalStringList != nil {
 		body.OptionalStringList = options.OptionalStringList
 	}
+	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	if err := runtime.MarshalAsJSON(req, body); err != nil {
 		return nil, err
 	}
diff --git a/packages/typespec-go/test/cadlranch/parameters/spreadgroup/zz_spreadmodel_client.go b/packages/typespec-go/test/cadlranch/parameters/spreadgroup/zz_spreadmodel_client.go
index 5b584c3f9..1c9fea657 100644
--- a/packages/typespec-go/test/cadlranch/parameters/spreadgroup/zz_spreadmodel_client.go
+++ b/packages/typespec-go/test/cadlranch/parameters/spreadgroup/zz_spreadmodel_client.go
@@ -53,12 +53,12 @@ func (client *SpreadModelClient) spreadAsRequestBodyCreateRequest(ctx context.Co
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	body := struct {
 		Name string `json:"name"`
 	}{
 		Name: name,
 	}
+	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	if err := runtime.MarshalAsJSON(req, body); err != nil {
 		return nil, err
 	}
@@ -101,8 +101,8 @@ func (client *SpreadModelClient) spreadCompositeRequestCreateRequest(ctx context
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	req.Raw().Header["test-header"] = []string{testHeader}
+	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	if err := runtime.MarshalAsJSON(req, body); err != nil {
 		return nil, err
 	}
@@ -145,13 +145,13 @@ func (client *SpreadModelClient) spreadCompositeRequestMixCreateRequest(ctx cont
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	req.Raw().Header["test-header"] = []string{testHeader}
 	body := struct {
 		Prop string `json:"prop"`
 	}{
 		Prop: prop,
 	}
+	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	if err := runtime.MarshalAsJSON(req, body); err != nil {
 		return nil, err
 	}
diff --git a/packages/typespec-go/test/cadlranch/payload/jmergepatchgroup/zz_jsonmergepatch_client.go b/packages/typespec-go/test/cadlranch/payload/jmergepatchgroup/zz_jsonmergepatch_client.go
index 61c53d788..1106a7a36 100644
--- a/packages/typespec-go/test/cadlranch/payload/jmergepatchgroup/zz_jsonmergepatch_client.go
+++ b/packages/typespec-go/test/cadlranch/payload/jmergepatchgroup/zz_jsonmergepatch_client.go
@@ -102,8 +102,8 @@ func (client *JSONMergePatchClient) updateOptionalResourceCreateRequest(ctx cont
 		return nil, err
 	}
 	req.Raw().Header["Accept"] = []string{"application/json"}
-	req.Raw().Header["Content-Type"] = []string{"application/merge-patch+json"}
 	if options != nil && options.Body != nil {
+		req.Raw().Header["Content-Type"] = []string{"application/merge-patch+json"}
 		if err := runtime.MarshalAsJSON(req, *options.Body); err != nil {
 			return nil, err
 		}
diff --git a/packages/typespec-go/test/cadlranch/payload/mediatypegroup/zz_mediatypestringbody_client.go b/packages/typespec-go/test/cadlranch/payload/mediatypegroup/zz_mediatypestringbody_client.go
index 8c27e97d5..dc053eaa7 100644
--- a/packages/typespec-go/test/cadlranch/payload/mediatypegroup/zz_mediatypestringbody_client.go
+++ b/packages/typespec-go/test/cadlranch/payload/mediatypegroup/zz_mediatypestringbody_client.go
@@ -192,8 +192,8 @@ func (client *MediaTypeStringBodyClient) sendAsTextCreateRequest(ctx context.Con
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"text/plain"}
 	body := streaming.NopCloser(strings.NewReader(textParam))
+	req.Raw().Header["Content-Type"] = []string{"text/plain"}
 	if err := req.SetBody(body, "text/plain"); err != nil {
 		return nil, err
 	}
diff --git a/packages/typespec-go/test/cadlranch/type/dictionarygroup/zz_dictionarydatetimevalue_client.go b/packages/typespec-go/test/cadlranch/type/dictionarygroup/zz_dictionarydatetimevalue_client.go
index 016c9af3a..e9b762d82 100644
--- a/packages/typespec-go/test/cadlranch/type/dictionarygroup/zz_dictionarydatetimevalue_client.go
+++ b/packages/typespec-go/test/cadlranch/type/dictionarygroup/zz_dictionarydatetimevalue_client.go
@@ -103,11 +103,11 @@ func (client *DictionaryDatetimeValueClient) putCreateRequest(ctx context.Contex
 	if err != nil {
 		return nil, err
 	}
-	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	aux := map[string]*dateTimeRFC3339{}
 	for k, v := range body {
 		aux[k] = (*dateTimeRFC3339)(v)
 	}
+	req.Raw().Header["Content-Type"] = []string{"application/json"}
 	if err := runtime.MarshalAsJSON(req, aux); err != nil {
 		return nil, err
 	}