diff --git a/.changeset/quick-laws-cover.md b/.changeset/quick-laws-cover.md
new file mode 100644
index 00000000..15281282
--- /dev/null
+++ b/.changeset/quick-laws-cover.md
@@ -0,0 +1,8 @@
+---
+"task-master-ai": minor
+---
+
+Add stricter validation and clearer feedback for task priority when adding new tasks
+
+- if a task priority is invalid, it will default to medium
+- made taks priority case-insensitive, essentially making HIGH and high the same value
diff --git a/scripts/modules/task-manager/add-task.js b/scripts/modules/task-manager/add-task.js
index 0fc29478..f3896532 100644
--- a/scripts/modules/task-manager/add-task.js
+++ b/scripts/modules/task-manager/add-task.js
@@ -29,6 +29,12 @@ import { generateObjectService } from '../ai-services-unified.js';
 import { getDefaultPriority } from '../config-manager.js';
 import ContextGatherer from '../utils/contextGatherer.js';
 import generateTaskFiles from './generate-task-files.js';
+import {
+	TASK_PRIORITY_OPTIONS,
+	DEFAULT_TASK_PRIORITY,
+	isValidTaskPriority,
+	normalizeTaskPriority
+} from '../../../src/constants/task-priority.js';
 
 // Define Zod schema for the expected AI output object
 const AiTaskDataSchema = z.object({
@@ -115,7 +121,25 @@ async function addTask(
 				success: (...args) => consoleLog('success', ...args)
 			};
 
-	const effectivePriority = priority || getDefaultPriority(projectRoot);
+	// Validate priority - only accept high, medium, or low
+	let effectivePriority =
+		priority || getDefaultPriority(projectRoot) || DEFAULT_TASK_PRIORITY;
+
+	// If priority is provided, validate and normalize it
+	if (priority) {
+		const normalizedPriority = normalizeTaskPriority(priority);
+		if (normalizedPriority) {
+			effectivePriority = normalizedPriority;
+		} else {
+			if (outputFormat === 'text') {
+				consoleLog(
+					'warn',
+					`Invalid priority "${priority}". Using default priority "${DEFAULT_TASK_PRIORITY}".`
+				);
+			}
+			effectivePriority = DEFAULT_TASK_PRIORITY;
+		}
+	}
 
 	logFn.info(
 		`Adding new task with prompt: "${prompt}", Priority: ${effectivePriority}, Dependencies: ${dependencies.join(', ') || 'None'}, Research: ${useResearch}, ProjectRoot: ${projectRoot}`
diff --git a/src/constants/task-priority.js b/src/constants/task-priority.js
new file mode 100644
index 00000000..0d766dd5
--- /dev/null
+++ b/src/constants/task-priority.js
@@ -0,0 +1,39 @@
+/**
+ * @typedef {'high' | 'medium' | 'low'} TaskPriority
+ */
+
+/**
+ * Task priority options
+ * @type {TaskPriority[]}
+ * @description Defines possible task priorities:
+ * - high: Critical tasks that need immediate attention
+ * - medium: Standard priority tasks (default)
+ * - low: Tasks that can be deferred or are nice-to-have
+ */
+export const TASK_PRIORITY_OPTIONS = ['high', 'medium', 'low'];
+
+/**
+ * Default task priority
+ * @type {TaskPriority}
+ */
+export const DEFAULT_TASK_PRIORITY = 'medium';
+
+/**
+ * Check if a given priority is valid
+ * @param {string} priority - The priority to check
+ * @returns {boolean} True if the priority is valid, false otherwise
+ */
+export function isValidTaskPriority(priority) {
+	return TASK_PRIORITY_OPTIONS.includes(priority?.toLowerCase());
+}
+
+/**
+ * Normalize a priority value to lowercase
+ * @param {string} priority - The priority to normalize
+ * @returns {TaskPriority|null} The normalized priority or null if invalid
+ */
+export function normalizeTaskPriority(priority) {
+	if (!priority) return null;
+	const normalized = priority.toLowerCase();
+	return isValidTaskPriority(normalized) ? normalized : null;
+}