diff --git a/src/PostalCodes.UnitTests/CountrySpecificPostalCodes/NLPostalCodeManualTests.cs b/src/PostalCodes.UnitTests/CountrySpecificPostalCodes/NLPostalCodeManualTests.cs
index 4acbae6..06284c1 100644
--- a/src/PostalCodes.UnitTests/CountrySpecificPostalCodes/NLPostalCodeManualTests.cs
+++ b/src/PostalCodes.UnitTests/CountrySpecificPostalCodes/NLPostalCodeManualTests.cs
@@ -6,10 +6,12 @@ namespace PostalCodes.UnitTests.CountrySpecificPostalCodes
     internal class NLPostalCodeManualTests
     {
         [Test]
-        [TestCase("9992 ZZ", "9991")]
+        [TestCase("9992 ZZ", "9992ZY")]
         [TestCase("9992", "9991")]
-        [TestCase("1000 ZZ", "0999")]
-        [TestCase("4000 ZZ", "3999")]
+        [TestCase("1000", "0999")]
+        [TestCase("1000 AA", "0999ZZ")]
+        [TestCase("4000 ZZ", "4000ZY")]
+        [TestCase("4000", "3999")]
         [TestCase("1422", "1421")]
         public void Predecessor_ValidInput_ReturnsCorrectPostalCode(string postalCode, string postalCodePredecessor)
         {
@@ -17,18 +19,22 @@ public void Predecessor_ValidInput_ReturnsCorrectPostalCode(string postalCode, s
         }
 
         [Test]
-        [TestCase("9992 ZZ", "9993")]
         [TestCase("9992", "9993")]
-        [TestCase("1000 ZZ", "1001")]
-        [TestCase("4000 ZZ", "4001")]
+        [TestCase("9992 ZZ", "9993AA")]
+        [TestCase("9992", "9993")]
+        [TestCase("1000", "1001")]
+        [TestCase("1000 ZZ", "1001AA")]
+        [TestCase("4000", "4001")]
+        [TestCase("4000 ZZ", "4001AA")]
         [TestCase("8999", "9000")]
+        [TestCase("8999AA", "8999AB")]
         public void Successor_ValidInput_ReturnsCorrectPostalCode(string postalCode, string postalCodeSuccessor)
         {
             Assert.AreEqual(postalCodeSuccessor, (new NLPostalCode(postalCode)).Successor.ToString());
         }
 
         [Test]
-        [TestCase("0000 ZZ")]
+        [TestCase("0000 AA")]
         [TestCase("0000")]
         public void Predecessor_FirstInRange_ReturnsNull(string postalCode)
         {
diff --git a/src/PostalCodes.UnitTests/Generated/NLPostalCodeTests.gen.cs b/src/PostalCodes.UnitTests/Generated/NLPostalCodeTests.gen.cs
index b9eb184..009e351 100644
--- a/src/PostalCodes.UnitTests/Generated/NLPostalCodeTests.gen.cs
+++ b/src/PostalCodes.UnitTests/Generated/NLPostalCodeTests.gen.cs
@@ -7,8 +7,10 @@ namespace PostalCodes.UnitTests.Generated
     internal class NLPostalCodeTests
     {
 
-        [TestCase("9999ZZ","9998")]
-        [TestCase("1000AA","0999")]
+        [TestCase("9999","9998")]
+        [TestCase("1000","0999")]
+        [TestCase("9999ZZ","9999ZY")]
+        [TestCase("1000AA","0999ZZ")]
         public void Predecessor_ValidInput_ReturnsCorrectPostalCode(string postalCode, string postalCodePredecessor)
         {
             var code = new NLPostalCode(postalCode);
@@ -18,8 +20,10 @@ public void Predecessor_ValidInput_ReturnsCorrectPostalCode(string postalCode, s
             Assert.AreEqual(codePredecessor.ToHumanReadableString(), code.Predecessor.ToHumanReadableString());
         }
 
-        [TestCase("0999ZZ","1000")]
-        [TestCase("3456JT","3457")]
+        [TestCase("0999","1000")]
+        [TestCase("3456","3457")]
+        [TestCase("0999ZZ","1000AA")]
+        [TestCase("3456JT","3456JU")]
         public void Successor_ValidInput_ReturnsCorrectPostalCode(string postalCode, string postalCodeSuccessor)
         {
             var code = new NLPostalCode(postalCode);
@@ -48,6 +52,11 @@ public void InvalidCode_ThrowsArgumentException(string postalCode)
             Assert.Throws<ArgumentException>(() => new NLPostalCode(postalCode));
         }
 
+        [TestCase("1234", "1236")]
+        [TestCase("1234AA", "1236AA")]
+        [TestCase("1235", "1237AA")]
+        [TestCase("1235ZY", "1235ZZ")]
+        [TestCase("1234ZZ", "1235")]
         public void CompareTo_ReturnsExpectedSign(string postalCodeBefore, string postalCodeAfter)
         {
             var b = new NLPostalCode(postalCodeBefore);
diff --git a/src/PostalCodes.UnitTests/PostalCodeFactoryTests.cs b/src/PostalCodes.UnitTests/PostalCodeFactoryTests.cs
index 5a34573..fead077 100644
--- a/src/PostalCodes.UnitTests/PostalCodeFactoryTests.cs
+++ b/src/PostalCodes.UnitTests/PostalCodeFactoryTests.cs
@@ -11,7 +11,8 @@ internal class PostalCodeFactoryTests
 		[TestCase("GB", "A1 9ZZ", "A19ZZ", "GBPostalCode")] // long
 		[TestCase("PT", "0042", "0042", "PTPostalCode")]
         [TestCase("CA", "A9A9A9", "A9A9A9", "CAPostalCode")]
-        [TestCase("NL", "0024 ZZ", "0024", "NLPostalCode")]
+        [TestCase("NL", "0024", "0024", "NLPostalCode")] // short NL
+        [TestCase("NL", "0024 ZZ", "0024ZZ", "NLPostalCode")] // long NL
         [TestCase("MT", "PLA1234", "PLA1234", "MTPostalCode")]
         [TestCase("??", "004", "004", "DefaultPostalCode")]
         public void CreatePostalCode_ReturnsCorrectObjectType(string country, string postalCode, string normalizedPostalCode, string objectTypeName)
diff --git a/src/PostalCodes/Generated/NLPostalCode.gen.cs b/src/PostalCodes/Generated/NLPostalCode.gen.cs
index 86aa8e3..bca3de9 100644
--- a/src/PostalCodes/Generated/NLPostalCode.gen.cs
+++ b/src/PostalCodes/Generated/NLPostalCode.gen.cs
@@ -40,7 +40,7 @@ public override int GetHashCode ()
                 RegexShort = new Regex("^[0-9]{4}$", RegexOptions.Compiled),
                 OutputDefault = "xxxx xx",
                 OutputShort = "xxxx",
-                AutoConvertToShort = true,
+                AutoConvertToShort = false,
                 ShortExpansionAsLowestInRange = "AA",
                 ShortExpansionAsHighestInRange = "ZZ",
                 LeftPaddingCharacter = "0",
diff --git a/src/countries/NL.json b/src/countries/NL.json
index ce1bafb..ef1bd15 100644
--- a/src/countries/NL.json
+++ b/src/countries/NL.json
@@ -14,7 +14,7 @@
 
                 "LeftPaddingCharacter" : "0",
 
-                "AutoConvertToShort" : "true",
+                "AutoConvertToShort" : "false",
                 "ShortExpansionAsLowestInRange" : "AA",
                 "ShortExpansionAsHighestInRange" : "ZZ"
             }
@@ -26,13 +26,24 @@
         "Valid" : ["1235DF", "5983DH"],
         "Invalid" : [ "12j4h", "k3j51l" ],
         "Predecessor" : {
-            "9999ZZ" : "9998",
-            "1000AA" : "0999"
+            "9999" : "9998",
+            "1000" : "0999",
+            "9999ZZ": "9999ZY",
+            "1000AA": "0999ZZ"
         },
         "Successor" : {
-            "0999ZZ" : "1000",
-            "3456JT" : "3457"
+            "0999" : "1000",
+            "3456" : "3457",
+            "0999ZZ": "1000AA",
+            "3456JT": "3456JU"
         },
-        "IsBefore" : {}
+        "IsBefore" : {
+          "1234": "1236",
+          "1234AA": "1234AB",
+          "1235": "1237AA",
+          "1234AA": "1236AA",
+          "1235ZY": "1235ZZ",
+          "1234ZZ": "1235"
+        }
     }
 }
\ No newline at end of file