diff --git a/common/changes/@rushstack/heft-typescript-plugin/heft-typescript-plugin-typescript-56-support_2024-10-13-22-44.json b/common/changes/@rushstack/heft-typescript-plugin/heft-typescript-plugin-typescript-56-support_2024-10-13-22-44.json
new file mode 100644
index 00000000000..9250e00f4ad
--- /dev/null
+++ b/common/changes/@rushstack/heft-typescript-plugin/heft-typescript-plugin-typescript-56-support_2024-10-13-22-44.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/heft-typescript-plugin",
+      "comment": "Support typescript v5.6",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@rushstack/heft-typescript-plugin"
+}
\ No newline at end of file
diff --git a/heft-plugins/heft-typescript-plugin/src/TypeScriptBuilder.ts b/heft-plugins/heft-typescript-plugin/src/TypeScriptBuilder.ts
index f1f4db242a9..4291e24cbcc 100644
--- a/heft-plugins/heft-typescript-plugin/src/TypeScriptBuilder.ts
+++ b/heft-plugins/heft-typescript-plugin/src/TypeScriptBuilder.ts
@@ -11,7 +11,11 @@ import { JsonFile, type IPackageJson, Path, FileError } from '@rushstack/node-co
 import type { ITerminal } from '@rushstack/terminal';
 import type { IScopedLogger } from '@rushstack/heft';
 
-import type { ExtendedTypeScript, IExtendedSolutionBuilder } from './internalTypings/TypeScriptInternals';
+import type {
+  ExtendedBuilderProgram,
+  ExtendedTypeScript,
+  IExtendedSolutionBuilder
+} from './internalTypings/TypeScriptInternals';
 import type { ITypeScriptConfigurationJson } from './TypeScriptPlugin';
 import type { PerformanceMeasurer } from './Performance';
 import type {
@@ -111,7 +115,7 @@ const OLDEST_SUPPORTED_TS_MAJOR_VERSION: number = 2;
 const OLDEST_SUPPORTED_TS_MINOR_VERSION: number = 9;
 
 const NEWEST_SUPPORTED_TS_MAJOR_VERSION: number = 5;
-const NEWEST_SUPPORTED_TS_MINOR_VERSION: number = 4;
+const NEWEST_SUPPORTED_TS_MINOR_VERSION: number = 6;
 
 interface ITypeScriptTool {
   ts: ExtendedTypeScript;
@@ -1300,9 +1304,10 @@ export class TypeScriptBuilder {
 function getFilesToTranspileFromBuilderProgram(
   builderProgram: TTypescript.BuilderProgram
 ): Map<string, string> {
-  const changedFilesSet: Set<string> = (
-    builderProgram as unknown as { getState(): { changedFilesSet: Set<string> } }
-  ).getState().changedFilesSet;
+  const program: ExtendedBuilderProgram = builderProgram as unknown as ExtendedBuilderProgram;
+  // getState was removed in Typescript 5.6, replaced with state
+  const changedFilesSet: Set<string> = (program.state ?? program.getState()).changedFilesSet;
+
   const filesToTranspile: Map<string, string> = new Map();
   for (const fileName of changedFilesSet) {
     const sourceFile: TTypescript.SourceFile | undefined = builderProgram.getSourceFile(fileName);
diff --git a/heft-plugins/heft-typescript-plugin/src/internalTypings/TypeScriptInternals.ts b/heft-plugins/heft-typescript-plugin/src/internalTypings/TypeScriptInternals.ts
index cfcc643e8a3..c330ac96769 100644
--- a/heft-plugins/heft-typescript-plugin/src/internalTypings/TypeScriptInternals.ts
+++ b/heft-plugins/heft-typescript-plugin/src/internalTypings/TypeScriptInternals.ts
@@ -98,3 +98,14 @@ export interface IExtendedTypeScript {
 }
 
 export type ExtendedTypeScript = typeof TTypescript & IExtendedTypeScript;
+
+export type ExtendedBuilderProgram = TTypescript.BuilderProgram & {
+  /**
+   * Typescript 5.6+
+   */
+  state?: { changedFilesSet: Set<string> };
+  /**
+   * Typescript < 5.6
+   */
+  getState(): { changedFilesSet: Set<string> };
+};