diff --git a/README.md b/README.md
index 64b657ad..95c8de94 100644
--- a/README.md
+++ b/README.md
@@ -65,6 +65,8 @@ To address this we've refactored exception handling and we are deprecating the g
 | 429  | XeroDailyRateLimitException            | The API daily rate limit for your organisation/application pairing has been exceeded.                                                   |
 | 429  | XeroMinuteRateLimitException           | The API minute rate limit for your organisation/application pairing has been exceeded.                                                  |
 | 500  | XeroServerErrorException               | An unhandled error with the Xero API                                                                                                    |
+| 501  | XeroNotImplementedException            | Method not implemented for the organisation                                                                                             |
+| 503  | XeroNotAvailableException              | The organisation temporarily cannot be connected to or API is currently unavailable – typically due to a scheduled outage               |
 
 Below is a try/catch example
 
diff --git a/src/main/java/com/xero/api/XeroApiExceptionHandler.java b/src/main/java/com/xero/api/XeroApiExceptionHandler.java
index 99cd323f..828a3682 100644
--- a/src/main/java/com/xero/api/XeroApiExceptionHandler.java
+++ b/src/main/java/com/xero/api/XeroApiExceptionHandler.java
@@ -210,10 +210,13 @@ public void execute(HttpResponseException e) {
             String message = "An error occurred in Xero. Check the API Status page http://status.developer.xero.com for current service status.";
             throw new XeroServerErrorException(statusCode, message, e);
 
-        } else if (statusCode > 500) {
-            String message = "Internal Server Error";
-            throw new XeroServerErrorException(statusCode, message, e);
-            
+        } else if (statusCode == 501) {
+            String message = "The method you have called has not been implemented";
+            throw new XeroNotImplementedException(statusCode, message, e);
+
+        } else if (statusCode == 503) {
+            throw new XeroNotAvailableException(statusCode, e.getStatusMessage(), e);
+
         } else {
             throw new XeroApiException(statusCode, e.getStatusMessage(), e);
         }
@@ -261,3 +264,4 @@ public void execute(HttpResponseException e, ApiClient apiClient)
     }
 
 }
+
diff --git a/src/main/java/com/xero/api/XeroNotAvailableException.java b/src/main/java/com/xero/api/XeroNotAvailableException.java
new file mode 100644
index 00000000..b01b74d6
--- /dev/null
+++ b/src/main/java/com/xero/api/XeroNotAvailableException.java
@@ -0,0 +1,37 @@
+package com.xero.api;
+
+/** handle not available exception  */
+public class XeroNotAvailableException extends XeroException {
+
+    private static final long serialVersionUID = 1L;
+    private int statusCode = 0;
+    private String message;
+
+    /** XeroNotAvailableException
+     * @param statusCode Integer the server status code returned.
+     * @param message String with details about the exception
+     * @param e Exception object with details about the original exception
+     */
+    public XeroNotAvailableException(int statusCode, String message, Exception e) {
+        super(statusCode + " : " + message, e);
+        this.statusCode = statusCode;
+        this.message = message;
+    }
+
+    /**
+     * get status code
+     * @return statusCode
+     **/
+    public int getStatusCode() {
+        return statusCode;
+    }
+
+    /**
+     * get message
+     * @return message
+     **/
+    public String getMessage() {
+        return message;
+    }
+
+}
diff --git a/src/main/java/com/xero/api/XeroNotImplementedException.java b/src/main/java/com/xero/api/XeroNotImplementedException.java
new file mode 100644
index 00000000..f0c94cc1
--- /dev/null
+++ b/src/main/java/com/xero/api/XeroNotImplementedException.java
@@ -0,0 +1,37 @@
+package com.xero.api;
+
+/** handle not available exception  */
+public class XeroNotImplementedException extends XeroException {
+
+    private static final long serialVersionUID = 1L;
+    private int statusCode = 0;
+    private String message;
+
+    /** XeroNotImplementedException
+     * @param statusCode Integer the server status code returned.
+     * @param message String with details about the exception
+     * @param e Exception object with details about the original exception
+     */
+    public XeroNotImplementedException(int statusCode, String message, Exception e) {
+        super(statusCode + " : " + message, e);
+        this.statusCode = statusCode;
+        this.message = message;
+    }
+
+    /**
+     * get status code
+     * @return statusCode
+     **/
+    public int getStatusCode() {
+        return statusCode;
+    }
+
+    /**
+     * get message
+     * @return message
+     **/
+    public String getMessage() {
+        return message;
+    }
+
+}
diff --git a/src/test/java/com/xero/api/XeroExceptionsTest.java b/src/test/java/com/xero/api/XeroExceptionsTest.java
index 090138cc..13c34ac0 100644
--- a/src/test/java/com/xero/api/XeroExceptionsTest.java
+++ b/src/test/java/com/xero/api/XeroExceptionsTest.java
@@ -196,6 +196,34 @@ public void testXeroServerErrorException() {
         xeroApiExceptionHandler.execute(httpResponseException);
     }
 
+    @Test
+    public void testXeroNotImplementedException() {
+        int statusCode = 501;
+        String message = "The method you have called has not been implemented";
+
+        // XeroNotImplementedException extends XeroException so we can catch either
+        expectedException.expect(XeroException.class);
+        expectedException.expect(XeroNotImplementedException.class);
+        expectedException.expectMessage(message);
+
+        when(httpResponseException.getStatusCode()).thenReturn(statusCode);
+        xeroApiExceptionHandler.execute(httpResponseException);
+    }
+
+
+    @Test
+    public void testXeroNotAvailableException() {
+        // 3 different messages can be returned with status code 503 so we won't check them
+        int statusCode = 503;
+
+        // XeroNotAvailableException extends XeroException so we can catch either
+        expectedException.expect(XeroException.class);
+        expectedException.expect(XeroNotAvailableException.class);
+
+        when(httpResponseException.getStatusCode()).thenReturn(statusCode);
+        xeroApiExceptionHandler.execute(httpResponseException);
+    }
+
     @Test
     public void testXeroApiException() {
         int statusCode = 1;
@@ -212,3 +240,4 @@ public void testXeroApiException() {
     }
 
 }
+