diff --git a/src/compositemark/boxplot.ts b/src/compositemark/boxplot.ts
index c281c9890eb..ef6bed38768 100644
--- a/src/compositemark/boxplot.ts
+++ b/src/compositemark/boxplot.ts
@@ -104,6 +104,8 @@ export function normalizeBoxPlot(
 
   const boxPlotType = getBoxPlotType(extent);
   const {
+    bins,
+    timeUnits,
     transform,
     continuousAxisChannelDef,
     continuousAxis,
@@ -300,17 +302,14 @@ export function normalizeBoxPlot(
       }
     })[0];
 
+    const filteredLayersMixinsTransforms = [...bins, ...timeUnits, joinaggregateTransform];
     if (outlierLayersMixins && filteredWhiskerSpec) {
       filteredLayersMixins = {
-        transform: [joinaggregateTransform],
+        transform: filteredLayersMixinsTransforms,
         layer: [outlierLayersMixins, filteredWhiskerSpec]
       };
-    } else if (outlierLayersMixins) {
-      filteredLayersMixins = outlierLayersMixins;
-      filteredLayersMixins.transform.unshift(joinaggregateTransform);
-    } else if (filteredWhiskerSpec) {
-      filteredLayersMixins = filteredWhiskerSpec;
-      filteredLayersMixins.transform.unshift(joinaggregateTransform);
+    } else if ((filteredLayersMixins = outlierLayersMixins || filteredWhiskerSpec)) {
+      filteredLayersMixins.transform.unshift(...filteredLayersMixinsTransforms);
     }
   }
 
@@ -423,6 +422,8 @@ function boxParams(
   ];
 
   return {
+    bins,
+    timeUnits,
     transform,
     groupby,
     aggregate,
diff --git a/test/compositemark/boxplot.test.ts b/test/compositemark/boxplot.test.ts
index d105e210682..6b19c5e1871 100644
--- a/test/compositemark/boxplot.test.ts
+++ b/test/compositemark/boxplot.test.ts
@@ -1070,4 +1070,31 @@ describe('normalizeBoxIQR', () => {
     const {tooltip} = normalizedSpecWithTooltip['layer'][0]['layer'][0]['encoding'];
     expect(tooltip).toEqual({field: 'year', type: 'quantitative'});
   });
+
+  it("should include timeUnit transform in filteredLayerMixins' transform", () => {
+    const field = 'Date';
+    const timeUnit = 'year';
+    const normalizedSpec = normalize(
+      {
+        data: {url: 'data/population.json'},
+        mark: 'boxplot',
+        encoding: {
+          x: {
+            field,
+            type: 'temporal',
+            timeUnit
+          },
+          y: {field: 'Anomaly', type: 'quantitative'}
+        }
+      },
+      defaultConfig
+    );
+
+    const filteredLayerMixins = normalizedSpec['layer'][1];
+    expect(filteredLayerMixins.transform[0]).toEqual({
+      timeUnit: {unit: 'year'},
+      field,
+      as: `${timeUnit}_${field}`
+    });
+  });
 });