diff --git a/src/NHapi.Base/Model/Primitive/TSComponentOne.cs b/src/NHapi.Base/Model/Primitive/TSComponentOne.cs
index 2a12073fa..2747d9c1e 100644
--- a/src/NHapi.Base/Model/Primitive/TSComponentOne.cs
+++ b/src/NHapi.Base/Model/Primitive/TSComponentOne.cs
@@ -73,9 +73,12 @@ public TSComponentOne(IMessage theMessage, string description)
 
         public override string Value
         {
+            // Reading Year, Month, Day and the other parts builds the parsed detail, which adds a
+            // default GMT offset to a value that has none. Return the stored value, so reading a
+            // part never changes it. The detail setters below write their result back here.
             get
             {
-                return (myDetail != null) ? myDetail.Value : base.Value;
+                return base.Value;
             }
 
             set
@@ -94,7 +97,11 @@ public override string Value
         /// </summary>
         public virtual int Offset
         {
-            set { Detail.Offset = value; }
+            set
+            {
+                Detail.Offset = value;
+                SyncValueFromDetail();
+            }
         }
 
         /// <summary>
@@ -194,6 +201,7 @@ public virtual void setDatePrecision(int yr, int mnth, int dy)
         public virtual void SetDatePrecision(int yr, int mnth, int dy)
         {
             Detail.SetDatePrecision(yr, mnth, dy);
+            SyncValueFromDetail();
         }
 
         [Obsolete("This method has been replaced by 'SetDateMinutePrecision'.")]
@@ -215,6 +223,7 @@ public virtual void setDateMinutePrecision(int yr, int mnth, int dy, int hr, int
         public virtual void SetDateMinutePrecision(int yr, int mnth, int dy, int hr, int min)
         {
             Detail.SetDateMinutePrecision(yr, mnth, dy, hr, min);
+            SyncValueFromDetail();
         }
 
         [Obsolete("This method has been replaced by 'SetDateSecondPrecision'.")]
@@ -236,6 +245,7 @@ public virtual void setDateSecondPrecision(int yr, int mnth, int dy, int hr, int
         public virtual void SetDateSecondPrecision(int yr, int mnth, int dy, int hr, int min, float sec)
         {
             Detail.SetDateSecondPrecision(yr, mnth, dy, hr, min, sec);
+            SyncValueFromDetail();
         }
 
         /// <summary>
@@ -315,5 +325,13 @@ public virtual void Set(DateTime value, string format)
                     "Could not format the date " + value + " to a long date.  Format must be " + LongDateTimeFormat);
             }
         }
+
+        /// <summary>
+        /// Stores the detail's value after one of its setters has changed it.
+        /// </summary>
+        private void SyncValueFromDetail()
+        {
+            base.Value = myDetail.Value;
+        }
     }
 }
\ No newline at end of file
diff --git a/tests/NHapi.NUnit/DtmPartsTest26.cs b/tests/NHapi.NUnit/DtmPartsTest26.cs
new file mode 100644
index 000000000..7b9ba715f
--- /dev/null
+++ b/tests/NHapi.NUnit/DtmPartsTest26.cs
@@ -0,0 +1,72 @@
+namespace NHapi.NUnit
+{
+    using System;
+
+    using global::NUnit.Framework;
+
+    using NHapi.Model.V26.Message;
+
+    /// <summary>
+    /// Reading the parts of a DTM must not change its value. See nHapiNET/nHapi#917.
+    /// </summary>
+    [TestFixture]
+    public class DtmPartsTest26
+    {
+        [TestCase("20100101")]
+        [TestCase("201001011230")]
+        [TestCase("20100101123045")]
+        [TestCase("20100101123045+0200")]
+        public void ReadingParts_DoesNotChangeValue(string value)
+        {
+            var pid = new ADT_A05().PID;
+            pid.DateTimeOfBirth.Value = value;
+
+            _ = pid.DateTimeOfBirth.Year;
+            _ = pid.DateTimeOfBirth.Month;
+            _ = pid.DateTimeOfBirth.Day;
+            _ = pid.DateTimeOfBirth.Hour;
+            _ = pid.DateTimeOfBirth.GMTOffset;
+
+            Assert.That(pid.DateTimeOfBirth.Value, Is.EqualTo(value));
+        }
+
+        [Test]
+        public void ReadingParts_ReturnsTheParts_AndGetAsDateStillWorks()
+        {
+            var pid = new ADT_A05().PID;
+            pid.DateTimeOfBirth.Value = "20100102";
+
+            Assert.That(pid.DateTimeOfBirth.Year, Is.EqualTo(2010));
+            Assert.That(pid.DateTimeOfBirth.Month, Is.EqualTo(1));
+            Assert.That(pid.DateTimeOfBirth.Day, Is.EqualTo(2));
+            Assert.That(pid.DateTimeOfBirth.GetAsDate(), Is.EqualTo(new DateTime(2010, 1, 2)));
+        }
+
+        [Test]
+        public void SettingValueAfterReadingParts_UpdatesTheParts()
+        {
+            var pid = new ADT_A05().PID;
+            pid.DateTimeOfBirth.Value = "20100102";
+            _ = pid.DateTimeOfBirth.Year;
+
+            pid.DateTimeOfBirth.Value = "19991231";
+
+            Assert.That(pid.DateTimeOfBirth.Value, Is.EqualTo("19991231"));
+            Assert.That(pid.DateTimeOfBirth.Year, Is.EqualTo(1999));
+            Assert.That(pid.DateTimeOfBirth.Day, Is.EqualTo(31));
+        }
+
+        [Test]
+        public void PrecisionSetters_StillUpdateValue()
+        {
+            var pid = new ADT_A05().PID;
+
+            pid.DateTimeOfBirth.SetDatePrecision(2010, 1, 2);
+            Assert.That(pid.DateTimeOfBirth.Value, Is.EqualTo("20100102"));
+
+            pid.DateTimeOfBirth.SetDateMinutePrecision(2010, 1, 2, 12, 30);
+            Assert.That(pid.DateTimeOfBirth.Value, Does.StartWith("201001021230"));
+            Assert.That(pid.DateTimeOfBirth.Minute, Is.EqualTo(30));
+        }
+    }
+}