diff --git a/Tasks/CombineAddresses.cs b/Tasks/CombineAddresses.cs
index d235f43..8fc17c0 100644
--- a/Tasks/CombineAddresses.cs
+++ b/Tasks/CombineAddresses.cs
@@ -92,4 +92,68 @@ public class CombineAddresses
 
         return first;
     }
+
+    /// <summary>
+    ///     Returns true if the addresses are the same.
+    /// </summary>
+    /// <param name="first">First address to compare</param>
+    /// <param name="second">Second address to compare</param>
+    /// <param name="only_refsid">If true, only a refsid-check will be done</param>
+    /// <returns></returns>
+    public bool CompareAddresses(KasPerson first, KasPerson second, bool only_refsid = false)
+    {
+        if (first.refsid == second.refsid) return true;
+        if (!only_refsid)
+            if (first.name == second.name &&
+                first.anrede == second.anrede &&
+                first.anredzus == second.anredzus &&
+                first.namezus == second.namezus &&
+                first.titel == second.titel &&
+                first.adel == second.adel &&
+                first.strasse == second.strasse &&
+                first.strasse2 == second.strasse2 &&
+                first.vorname == second.vorname &&
+                first.ort == second.ort &&
+                first.land == second.land &&
+                first.plz == second.plz &&
+                first.pplz == second.pplz &&
+                first.funktion == second.funktion &&
+                first.funktion2 == second.funktion2 &&
+                first.funktionad == second.funktionad &&
+                first.abteilung == second.abteilung &&
+                first.postfach == second.postfach &&
+                first.name1 == second.name1 &&
+                first.name2 == second.name2 &&
+                first.name3 == second.name3 &&
+                first.name4 == second.name4 &&
+                first.name5 == second.name5)
+                return true;
+
+        return false;
+    }
+
+    public async Task<KasAddressList> Difference()
+    {
+        return null;
+    }
+
+    public async Task<KasAddressList> Union()
+    {
+        return null;
+    }
+
+    public async Task<KasAddressList> MoveDuplicatesToNew()
+    {
+        return null;
+    }
+
+    public async Task<KasAddressList> Intersection()
+    {
+        return null;
+    }
+
+    public async Task<KasAddressList> SymmetricDifference()
+    {
+        return null;
+    }
 }
\ No newline at end of file