diff --git a/docs/generators/csharp-netcore.md b/docs/generators/csharp-netcore.md
index 7b67601f3d3c..8cf2d0ee54ad 100644
--- a/docs/generators/csharp-netcore.md
+++ b/docs/generators/csharp-netcore.md
@@ -25,7 +25,7 @@ sidebar_label: csharp-netcore
 |returnICollection|Return ICollection<T> instead of the concrete type.| |false|
 |sortParamsByRequiredFlag|Sort method arguments to place required parameters before optional parameters.| |true|
 |sourceFolder|source folder for generated code| |src|
-|targetFramework|The target .NET framework version.|<dl><dt>**netstandard1.3**</dt><dd>.NET Standard 1.3 compatible</dd><dt>**netstandard1.4**</dt><dd>.NET Standard 1.4 compatible</dd><dt>**netstandard1.5**</dt><dd>.NET Standard 1.5 compatible</dd><dt>**netstandard1.6**</dt><dd>.NET Standard 1.6 compatible</dd><dt>**netstandard2.0**</dt><dd>.NET Standard 2.0 compatible</dd><dt>**netcoreapp2.0**</dt><dd>.NET Core 2.0 compatible</dd><dl>|netstandard2.0|
+|targetFramework|The target .NET framework version.|<dl><dt>**netstandard1.3**</dt><dd>.NET Standard 1.3 compatible</dd><dt>**netstandard1.4**</dt><dd>.NET Standard 1.4 compatible</dd><dt>**netstandard1.5**</dt><dd>.NET Standard 1.5 compatible</dd><dt>**netstandard1.6**</dt><dd>.NET Standard 1.6 compatible</dd><dt>**netstandard2.0**</dt><dd>.NET Standard 2.0 compatible</dd><dt>**netstandard2.1**</dt><dd>.NET Standard 2.1 compatible</dd><dt>**netcoreapp2.0**</dt><dd>.NET Core 2.0 compatible</dd><dt>**netcoreapp2.1**</dt><dd>.NET Core 2.1 compatible</dd><dt>**netcoreapp3.0**</dt><dd>.NET Core 3.0 compatible</dd><dt>**netcoreapp3.1**</dt><dd>.NET Core 3.1 compatible</dd><dl>|netstandard2.0|
 |useCollection|Deserialize array types to Collection&lt;T&gt; instead of List&lt;T&gt;.| |false|
 |useDateTimeOffset|Use DateTimeOffset to model date-time properties| |false|
 |validatable|Generates self-validatable models.| |true|
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CSharpNetCoreClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CSharpNetCoreClientCodegen.java
index f17168d19d78..95ced94f2f8e 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CSharpNetCoreClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CSharpNetCoreClientCodegen.java
@@ -56,7 +56,11 @@ public class CSharpNetCoreClientCodegen extends AbstractCSharpCodegen {
             FrameworkStrategy.NETSTANDARD_1_5,
             FrameworkStrategy.NETSTANDARD_1_6,
             FrameworkStrategy.NETSTANDARD_2_0,
-            FrameworkStrategy.NETCOREAPP_2_0
+            FrameworkStrategy.NETSTANDARD_2_1,
+            FrameworkStrategy.NETCOREAPP_2_0,
+            FrameworkStrategy.NETCOREAPP_2_1,
+            FrameworkStrategy.NETCOREAPP_3_0,
+            FrameworkStrategy.NETCOREAPP_3_1
     );
     private static FrameworkStrategy defaultFramework = FrameworkStrategy.NETSTANDARD_2_0;
     protected final Map<String, String> frameworks;
@@ -67,6 +71,7 @@ public class CSharpNetCoreClientCodegen extends AbstractCSharpCodegen {
 
     // Defines TargetFrameworkVersion in csproj files
     protected String targetFramework = defaultFramework.name;
+    protected String testTargetFramework = defaultFramework.testTargetFramework;
 
     // Defines nuget identifiers for target framework
     protected String targetFrameworkNuget = targetFramework;
@@ -548,6 +553,7 @@ public void processOpts() {
 
         setTargetFrameworkNuget(strategy.getNugetFrameworkIdentifier());
         setTargetFramework(strategy.name);
+        setTestTargetFramework(strategy.testTargetFramework);
 
         if (strategy != FrameworkStrategy.NETSTANDARD_2_0) {
             LOGGER.warn("If using built-in templates-RestSharp only supports netstandard 2.0 or later.");
@@ -571,6 +577,7 @@ public void processOpts() {
         syncStringProperty(additionalProperties, CodegenConstants.MODEL_PACKAGE, this::setModelPackage, modelPackage);
         syncStringProperty(additionalProperties, CodegenConstants.OPTIONAL_PROJECT_GUID, this::setPackageGuid, packageGuid);
         syncStringProperty(additionalProperties, "targetFrameworkNuget", this::setTargetFrameworkNuget, this.targetFrameworkNuget);
+        syncStringProperty(additionalProperties, "testTargetFramework", this::setTestTargetFramework, this.testTargetFramework);
 
         syncBooleanProperty(additionalProperties, "netStandard", this::setNetStandard, this.netStandard);
 
@@ -702,6 +709,10 @@ public void setTargetFramework(String dotnetFramework) {
         LOGGER.info("Generating code for .NET Framework " + this.targetFramework);
     }
 
+    public void setTestTargetFramework(String testTargetFramework) {
+        this.testTargetFramework = testTargetFramework;
+    }
+
     public void setTargetFrameworkNuget(String targetFrameworkNuget) {
         this.targetFrameworkNuget = targetFrameworkNuget;
     }
@@ -854,34 +865,41 @@ private void syncStringProperty(final Map<String, Object> additionalProperties,
     // https://docs.microsoft.com/en-us/dotnet/standard/net-standard
     @SuppressWarnings("Duplicates")
     private static abstract class FrameworkStrategy {
-        static FrameworkStrategy NETSTANDARD_1_3 = new FrameworkStrategy("netstandard1.3", ".NET Standard 1.3 compatible", "v4.6.1") {
+        static FrameworkStrategy NETSTANDARD_1_3 = new FrameworkStrategy("netstandard1.3", ".NET Standard 1.3 compatible", "netcoreapp2.0") {
         };
-        static FrameworkStrategy NETSTANDARD_1_4 = new FrameworkStrategy("netstandard1.4", ".NET Standard 1.4 compatible", "v4.6.1") {
+        static FrameworkStrategy NETSTANDARD_1_4 = new FrameworkStrategy("netstandard1.4", ".NET Standard 1.4 compatible", "netcoreapp2.0") {
         };
-        static FrameworkStrategy NETSTANDARD_1_5 = new FrameworkStrategy("netstandard1.5", ".NET Standard 1.5 compatible", "v4.6.1") {
+        static FrameworkStrategy NETSTANDARD_1_5 = new FrameworkStrategy("netstandard1.5", ".NET Standard 1.5 compatible", "netcoreapp2.0") {
         };
-        static FrameworkStrategy NETSTANDARD_1_6 = new FrameworkStrategy("netstandard1.6", ".NET Standard 1.6 compatible", "v4.6.1") {
+        static FrameworkStrategy NETSTANDARD_1_6 = new FrameworkStrategy("netstandard1.6", ".NET Standard 1.6 compatible", "netcoreapp2.0") {
         };
-        static FrameworkStrategy NETSTANDARD_2_0 = new FrameworkStrategy("netstandard2.0", ".NET Standard 2.0 compatible", "v4.6.1") {
+        static FrameworkStrategy NETSTANDARD_2_0 = new FrameworkStrategy("netstandard2.0", ".NET Standard 2.0 compatible", "netcoreapp2.0") {
         };
-        static FrameworkStrategy NETCOREAPP_2_0 = new FrameworkStrategy("netcoreapp2.0", ".NET Core 2.0 compatible", "v4.6.1", Boolean.FALSE) {
-
+        static FrameworkStrategy NETSTANDARD_2_1 = new FrameworkStrategy("netstandard2.1", ".NET Standard 2.1 compatible", "netcoreapp3.0") {
+        };
+        static FrameworkStrategy NETCOREAPP_2_0 = new FrameworkStrategy("netcoreapp2.0", ".NET Core 2.0 compatible", "netcoreapp2.0", Boolean.FALSE) {
+        };
+        static FrameworkStrategy NETCOREAPP_2_1 = new FrameworkStrategy("netcoreapp2.1", ".NET Core 2.1 compatible", "netcoreapp2.1", Boolean.FALSE) {
+        };
+        static FrameworkStrategy NETCOREAPP_3_0 = new FrameworkStrategy("netcoreapp3.0", ".NET Core 3.0 compatible", "netcoreapp3.0", Boolean.FALSE) {
+        };
+        static FrameworkStrategy NETCOREAPP_3_1 = new FrameworkStrategy("netcoreapp3.1", ".NET Core 3.1 compatible", "netcoreapp3.1", Boolean.FALSE) {
         };
         protected String name;
         protected String description;
-        protected String dotNetFrameworkVersion;
+        protected String testTargetFramework;
         private Boolean isNetStandard = Boolean.TRUE;
 
-        FrameworkStrategy(String name, String description, String dotNetFrameworkVersion) {
+        FrameworkStrategy(String name, String description, String testTargetFramework) {
             this.name = name;
             this.description = description;
-            this.dotNetFrameworkVersion = dotNetFrameworkVersion;
+            this.testTargetFramework = testTargetFramework;
         }
 
-        FrameworkStrategy(String name, String description, String dotNetFrameworkVersion, Boolean isNetStandard) {
+        FrameworkStrategy(String name, String description, String testTargetFramework, Boolean isNetStandard) {
             this.name = name;
             this.description = description;
-            this.dotNetFrameworkVersion = dotNetFrameworkVersion;
+            this.testTargetFramework = testTargetFramework;
             this.isNetStandard = isNetStandard;
         }
 
diff --git a/modules/openapi-generator/src/main/resources/csharp-netcore/TestProject.mustache b/modules/openapi-generator/src/main/resources/csharp-netcore/TestProject.mustache
index 9ef7ae726ae9..a5d124698075 100644
--- a/modules/openapi-generator/src/main/resources/csharp-netcore/TestProject.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp-netcore/TestProject.mustache
@@ -17,8 +17,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>{{testPackageName}}</RootNamespace>
     <AssemblyName>{{testPackageName}}</AssemblyName>
-    <!-- By Microsoft design, test project can only be netcoreapp2.0 (even if main project is .netstandard -->
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>{{testTargetFramework}}</TargetFramework>
     <IsPackable>false</IsPackable>
     <FileAlignment>512</FileAlignment>
   </PropertyGroup>
diff --git a/modules/openapi-generator/src/main/resources/csharp-netcore/netcore_testproject.mustache b/modules/openapi-generator/src/main/resources/csharp-netcore/netcore_testproject.mustache
index aa4f8beb8b03..d6faf0b43f97 100644
--- a/modules/openapi-generator/src/main/resources/csharp-netcore/netcore_testproject.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp-netcore/netcore_testproject.mustache
@@ -13,7 +13,7 @@
     <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
     <GenerateBindingRedirectsOutputType>true</GenerateBindingRedirectsOutputType>
     <RootNamespace>{{testPackageName}}</RootNamespace>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>{{testTargetFramework}}</TargetFramework>
     <IsPackable>false</IsPackable>
   </PropertyGroup>