diff --git a/messages/de.json b/messages/de.json
index 2e80dbaad..29e955a0f 100644
--- a/messages/de.json
+++ b/messages/de.json
@@ -676,7 +676,8 @@
     "insightsCallout": {
       "lastMonth": "Vergleich zum Vormonat aktiv",
       "lastYear": "Vergleich zum Vorjahr aktiv"
-    }
+    },
+    "notAvailableForCompliance": "Vergleich für Compliance nicht verfügbar"
   },
   "insights": {
     "aiAnalysisTitle": "KI-Gesundheitsanalyse",
diff --git a/messages/en.json b/messages/en.json
index 8260c4018..1b9f647ff 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -676,7 +676,8 @@
     "insightsCallout": {
       "lastMonth": "Tracking against last month",
       "lastYear": "Tracking against last year"
-    }
+    },
+    "notAvailableForCompliance": "Comparison N/A for compliance"
   },
   "insights": {
     "aiAnalysisTitle": "AI Health Analysis",
diff --git a/src/app/page.tsx b/src/app/page.tsx
index 247615aa6..ebde5fc6b 100644
--- a/src/app/page.tsx
+++ b/src/app/page.tsx
@@ -994,7 +994,12 @@ export default function DashboardPage() {
           charts.push({
             id: "medications",
             order: widgetOrder("medications"),
-            node: <MedicationComplianceChart key="medications" />,
+            node: (
+              <MedicationComplianceChart
+                key="medications"
+                compareBaseline={compareBaseline}
+              />
+            ),
           });
         }
         if (showAchievementsCard) {
diff --git a/src/components/charts/medication-compliance-chart.tsx b/src/components/charts/medication-compliance-chart.tsx
index 6e89e742f..0a307b642 100644
--- a/src/components/charts/medication-compliance-chart.tsx
+++ b/src/components/charts/medication-compliance-chart.tsx
@@ -152,10 +152,22 @@ export function computeMedicationTrend7d(
 interface MedicationComplianceChartProps {
   /** Override the visible label, primarily for tests. */
   title?: string;
+  /**
+   * v1.4.16 phase D reconcile (H4 design) — when the user toggles the
+   * dashboard comparison overlay, every other chart paints a dimmed
+   * prior-period line. Compliance is a percentage-of-doses metric whose
+   * "prior month" overlay would need a second window of intake events
+   * (deferred to v1.4.17). We accept the prop so the parent doesn't
+   * have to special-case this chart, and surface a small caption when
+   * comparison is on so the user understands the asymmetry rather than
+   * thinking the toggle is broken.
+   */
+  compareBaseline?: "none" | "lastMonth" | "lastYear";
 }
 
 export function MedicationComplianceChart({
   title,
+  compareBaseline = "none",
 }: MedicationComplianceChartProps) {
   const { isAuthenticated } = useAuth();
   const { t } = useTranslations();
@@ -266,6 +278,22 @@ export function MedicationComplianceChart({
         </div>
       </div>
 
+      {/* v1.4.16 phase D reconcile (H4 design) — explicit "comparison
+          N/A" caption when the global toggle is on. The compliance
+          heatmap doesn't render a prior-period overlay (deferred to
+          v1.4.17 when the underlying intake-event window comparison
+          ships). Without this caption the user toggles Vormonat and
+          this card just stays static, which reads as a bug. */}
+      {compareBaseline !== "none" && (
+        <p
+          className="text-muted-foreground -mt-2 mb-3 text-xs"
+          data-slot="medication-comparison-na"
+          data-compare-baseline={compareBaseline}
+        >
+          {t("comparison.notAvailableForCompliance")}
+        </p>
+      )}
+
       {/* v1.4.16 B1a — sibling SVG <defs> block for SSR-discoverable
           gradient. */}
       <svg