diff --git a/sql/reports/challenges/challenges-history.sql b/sql/reports/challenges/challenges-history.sql
index aece5c9..c43416b 100644
--- a/sql/reports/challenges/challenges-history.sql
+++ b/sql/reports/challenges/challenges-history.sql
@@ -4,13 +4,21 @@ SELECT
   c.groups as "groupNames",
   c.status as "challengeStatus",
   c."registrationStartDate" as "registrationStartDate",
-  CASE WHEN c.status = 'COMPLETED' THEN
-    (SELECT cp."actualEndDate" FROM challenges."ChallengePhase" cp WHERE cp."challengeId"=c.id ORDER BY cp."scheduledEndDate" DESC LIMIT 1)
-    ELSE null END as "challengeCompletionDate",
+  CASE
+    WHEN c.status = 'COMPLETED' THEN latest_phase."actualEndDate"
+    ELSE null
+  END as "challengeCompletionDate",
   c.tags as "tags",
   c."projectId" as "projectId"
 FROM
   challenges."Challenge" c
+LEFT JOIN LATERAL (
+  SELECT cp."actualEndDate"
+  FROM challenges."ChallengePhase" cp
+  WHERE cp."challengeId" = c.id
+  ORDER BY cp."scheduledEndDate" DESC
+  LIMIT 1
+) latest_phase ON true
 LEFT JOIN
   challenges."ChallengeBilling" cb on cb."challengeId"=c.id
 -- filter by billing account
@@ -19,40 +27,13 @@ WHERE ($1::text[] IS NULL OR cb."billingAccountId" = ANY($1::text[]))
   AND ($2::text[] IS NULL OR cb."billingAccountId" <> ANY($2::text[]))
   -- filter by challenge status
   AND ($3::text[] IS NULL OR c.status::text= ANY($3::text[]))
-  -- -- filter by completion date
-  -- filter by challengeCompletedDate
-  AND (c.status!='COMPLETED' OR (
+  -- filter by completion date bounds on the latest challenge phase end date
+  AND (
     ($4::timestamptz IS NULL AND $5::timestamptz IS NULL)
     OR (
-      $5::timestamptz IS NULL AND (
-        (
-          SELECT cp."actualEndDate"
-          FROM challenges."ChallengePhase" cp
-          WHERE cp."challengeId" = c.id
-          ORDER BY cp."scheduledEndDate" DESC
-          LIMIT 1
-        ) >= $4::timestamptz
-      )
+      latest_phase."actualEndDate" IS NOT NULL
+      AND ($4::timestamptz IS NULL OR latest_phase."actualEndDate" >= $4::timestamptz)
+      AND ($5::timestamptz IS NULL OR latest_phase."actualEndDate" <= $5::timestamptz)
     )
-    OR (
-      $4::timestamptz IS NULL AND $5::timestamptz IS NOT NULL AND (
-        (
-          SELECT cp."actualEndDate"
-          FROM challenges."ChallengePhase" cp
-          WHERE cp."challengeId" = c.id
-          ORDER BY cp."scheduledEndDate" DESC
-          LIMIT 1
-        ) >= $5::timestamptz
-      )
-    )
-    OR (
-      $4::timestamptz IS NOT NULL AND $5::timestamptz IS NOT NULL AND ((
-        SELECT cp."actualEndDate"
-        FROM challenges."ChallengePhase" cp
-        WHERE cp."challengeId" = c.id
-        ORDER BY cp."scheduledEndDate" DESC
-        LIMIT 1
-      ) BETWEEN $4::timestamptz AND $5::timestamptz)
-    )
-  ))
+  )
 LIMIT 1000;
diff --git a/sql/reports/challenges/registrants-history.sql b/sql/reports/challenges/registrants-history.sql
index 0ceb7ac..943e6c5 100644
--- a/sql/reports/challenges/registrants-history.sql
+++ b/sql/reports/challenges/registrants-history.sql
@@ -3,13 +3,21 @@ SELECT
   c.status as "challengeStatus",
   cw.handle as "winnerHandle",
   CASE WHEN sub.placement = 1 THEN true ELSE false END as "isWinner",
-  CASE WHEN c.status = 'COMPLETED' THEN
-    (SELECT cp."actualEndDate" FROM challenges."ChallengePhase" cp WHERE cp."challengeId"=c.id ORDER BY cp."scheduledEndDate" DESC LIMIT 1)
-    ELSE null END as "challengeCompletedDate",
+  CASE
+    WHEN c.status = 'COMPLETED' THEN latest_phase."actualEndDate"
+    ELSE null
+  END as "challengeCompletedDate",
   res."memberHandle" as "registrantHandle",
   ROUND(sub."finalScore", 2) as "registrantFinalScore"
 FROM
   challenges."Challenge" c
+LEFT JOIN LATERAL (
+  SELECT cp."actualEndDate"
+  FROM challenges."ChallengePhase" cp
+  WHERE cp."challengeId" = c.id
+  ORDER BY cp."scheduledEndDate" DESC
+  LIMIT 1
+) latest_phase ON true
 LEFT JOIN
   resources."Resource" res ON c.id = res."challengeId"
 LEFT JOIN
@@ -27,40 +35,13 @@ WHERE rr.name = 'Submitter'
   AND ($2::text[] IS NULL OR cb."billingAccountId" <> ANY($2::text[]))
   -- filter by challenge status
   AND ($3::text[] IS NULL OR c.status::text= ANY($3::text[]))
-  -- -- filter by completion date
-  -- filter by challengeCompletedDate
-  AND (c.status!='COMPLETED' OR (
+  -- filter by completion date bounds on the latest challenge phase end date
+  AND (
     ($4::timestamptz IS NULL AND $5::timestamptz IS NULL)
     OR (
-      $5::timestamptz IS NULL AND (
-        (
-          SELECT cp."actualEndDate"
-          FROM challenges."ChallengePhase" cp
-          WHERE cp."challengeId" = c.id
-          ORDER BY cp."scheduledEndDate" DESC
-          LIMIT 1
-        ) >= $4::timestamptz
-      )
+      latest_phase."actualEndDate" IS NOT NULL
+      AND ($4::timestamptz IS NULL OR latest_phase."actualEndDate" >= $4::timestamptz)
+      AND ($5::timestamptz IS NULL OR latest_phase."actualEndDate" <= $5::timestamptz)
     )
-    OR (
-      $4::timestamptz IS NULL AND $5::timestamptz IS NOT NULL AND (
-        (
-          SELECT cp."actualEndDate"
-          FROM challenges."ChallengePhase" cp
-          WHERE cp."challengeId" = c.id
-          ORDER BY cp."scheduledEndDate" DESC
-          LIMIT 1
-        ) >= $5::timestamptz
-      )
-    )
-    OR (
-      $4::timestamptz IS NOT NULL AND $5::timestamptz IS NOT NULL AND ((
-        SELECT cp."actualEndDate"
-        FROM challenges."ChallengePhase" cp
-        WHERE cp."challengeId" = c.id
-        ORDER BY cp."scheduledEndDate" DESC
-        LIMIT 1
-      ) BETWEEN $4::timestamptz AND $5::timestamptz)
-    )
-  ))
+  )
 LIMIT 1000;