diff --git a/src/State/EmployeeLeaveSummaryProvider.php b/src/State/EmployeeLeaveSummaryProvider.php
index 0292a1a..f7fd33e 100644
--- a/src/State/EmployeeLeaveSummaryProvider.php
+++ b/src/State/EmployeeLeaveSummaryProvider.php
@@ -545,6 +545,25 @@ final readonly class EmployeeLeaveSummaryProvider implements ProviderInterface
         return $phases[0];
     }
 
+    /**
+     * Phase dont la date de début est la plus proche en deçà de celle de $phase
+     * (la phase qui précède immédiatement). Null si $phase est la première.
+     */
+    private function resolvePhaseImmediatelyBefore(Employee $employee, ContractPhase $phase): ?ContractPhase
+    {
+        $prior = null;
+        foreach ($this->phaseResolver->resolvePhases($employee) as $candidate) {
+            if ($candidate->startDate >= $phase->startDate) {
+                continue;
+            }
+            if (null === $prior || $candidate->startDate > $prior->startDate) {
+                $prior = $candidate;
+            }
+        }
+
+        return $prior;
+    }
+
     /**
      * @param list<ContractSuspension>                                      $suspensions
      * @param list<array{start: DateTimeImmutable, end: DateTimeImmutable}> $longMaladiePeriods
diff --git a/tests/State/EmployeeLeaveSummaryProviderTest.php b/tests/State/EmployeeLeaveSummaryProviderTest.php
index 8a2347f..6d4fbb0 100644
--- a/tests/State/EmployeeLeaveSummaryProviderTest.php
+++ b/tests/State/EmployeeLeaveSummaryProviderTest.php
@@ -247,6 +247,31 @@ final class EmployeeLeaveSummaryProviderTest extends TestCase
         self::assertFalse($this->invokePrivate($provider, 'isForfaitEntryYear', $h39Phase, 2026));
     }
 
+    public function testResolvePhaseImmediatelyBeforeReturnsPriorH39Phase(): void
+    {
+        $employee     = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $phases       = new EmployeeContractPhaseResolver()->resolvePhases($employee);
+        $forfaitPhase = $phases[0]; // current FORFAIT
+        $h39Phase     = $phases[1];
+        $provider     = $this->buildProvider();
+
+        $prior = $this->invokePrivate($provider, 'resolvePhaseImmediatelyBefore', $employee, $forfaitPhase);
+
+        self::assertNotNull($prior);
+        self::assertSame($h39Phase->id, $prior->id);
+        self::assertSame(ContractType::H39, $prior->contractType);
+    }
+
+    public function testResolvePhaseImmediatelyBeforeReturnsNullForFirstPhase(): void
+    {
+        $employee   = $this->buildEmployeeWithTransition('2020-06-01', '2026-04-30', '2026-05-01');
+        $phases     = new EmployeeContractPhaseResolver()->resolvePhases($employee);
+        $firstPhase = $phases[1]; // the H39 (earliest)
+        $provider   = $this->buildProvider();
+
+        self::assertNull($this->invokePrivate($provider, 'resolvePhaseImmediatelyBefore', $employee, $firstPhase));
+    }
+
     public function testNonForfaitPhaseStartingMidExerciseUsesFullExerciseFromAsStart(): void
     {
         // Scenario: 35h CDI from 2014-07-01 to 2025-10-31, then 39h CDI from 2025-11-01.