diff --git a/plugins/cost-insights/src/utils/duration.test.ts b/plugins/cost-insights/src/utils/duration.test.ts
index 45d8e5b6a3..47769a45f1 100644
--- a/plugins/cost-insights/src/utils/duration.test.ts
+++ b/plugins/cost-insights/src/utils/duration.test.ts
@@ -15,7 +15,11 @@
  */
 
 import { Duration } from '../types';
-import { inclusiveEndDateOf, inclusiveStartDateOf } from './duration';
+import {
+  inclusiveEndDateOf,
+  inclusiveStartDateOf,
+  quarterEndDate,
+} from './duration';
 
 const lastCompleteBillingDate = '2020-06-05';
 
@@ -32,3 +36,14 @@ describe.each`
     expect(inclusiveEndDateOf(duration, lastCompleteBillingDate)).toBe(endDate);
   });
 });
+
+describe.each`
+  inclusiveEndDate | expectedQuarterEndDate
+  ${'2020-12-31'}  | ${'2020-12-31'}
+  ${'2020-12-30'}  | ${'2020-09-30'}
+  ${'2021-02-19'}  | ${'2020-12-31'}
+`('quarterEndDate', ({ inclusiveEndDate, expectedQuarterEndDate }) => {
+  it(`calculates quarter end date correctly from inclusive end date ${inclusiveEndDate}`, () => {
+    expect(quarterEndDate(inclusiveEndDate)).toBe(expectedQuarterEndDate);
+  });
+});
diff --git a/plugins/cost-insights/src/utils/duration.ts b/plugins/cost-insights/src/utils/duration.ts
index 0d9d6aa179..7a330b6f91 100644
--- a/plugins/cost-insights/src/utils/duration.ts
+++ b/plugins/cost-insights/src/utils/duration.ts
@@ -60,7 +60,10 @@ export function exclusiveEndDateOf(
         .add(1, 'day')
         .format(DEFAULT_DATE_FORMAT);
     case Duration.P3M:
-      return quarterEndDate(inclusiveEndDate);
+      return moment(quarterEndDate(inclusiveEndDate))
+        .utc()
+        .add(1, 'day')
+        .format(DEFAULT_DATE_FORMAT);
     default:
       return assertNever(duration);
   }
@@ -81,11 +84,14 @@ export function intervalsOf(duration: Duration, inclusiveEndDate: string) {
   return `R2/${duration}/${exclusiveEndDateOf(duration, inclusiveEndDate)}`;
 }
 
-function quarterEndDate(inclusiveEndDate: string): string {
+export function quarterEndDate(inclusiveEndDate: string): string {
   const endDate = moment(inclusiveEndDate).utc();
   const endOfQuarter = endDate.endOf('quarter').format(DEFAULT_DATE_FORMAT);
   if (endOfQuarter === inclusiveEndDate) {
-    return endDate.add(1, 'day').format(DEFAULT_DATE_FORMAT);
+    return endDate.format(DEFAULT_DATE_FORMAT);
   }
-  return endDate.startOf('quarter').format(DEFAULT_DATE_FORMAT);
+  return endDate
+    .startOf('quarter')
+    .subtract(1, 'day')
+    .format(DEFAULT_DATE_FORMAT);
 }