diff --git a/src/Invoice/Hydrator/InvoiceModelDefaultHydrator.php b/src/Invoice/Hydrator/InvoiceModelDefaultHydrator.php
index 8d808e9e..82aaddde 100644
--- a/src/Invoice/Hydrator/InvoiceModelDefaultHydrator.php
+++ b/src/Invoice/Hydrator/InvoiceModelDefaultHydrator.php
@@ -90,6 +90,27 @@ class InvoiceModelDefaultHydrator implements InvoiceModelHydrator
             ]);
         }
 
+        $entries = $model->getEntries();
+        $min = null;
+        $max = null;
+
+        foreach ($entries as $entry) {
+            if ($min === null || $min->getBegin()->getTimestamp() > $entry->getBegin()->getTimestamp()) {
+                $min = $entry;
+            }
+
+            if ($max === null || $max->getBegin()->getTimestamp() < $entry->getBegin()->getTimestamp()) {
+                $max = $entry;
+            }
+        }
+
+        if ($min !== null && $max !== null) {
+            $values = array_merge($values, [
+                'invoice.first' => $formatter->getFormattedDateTime($min->getBegin()),
+                'invoice.last' => $formatter->getFormattedDateTime($max->getEnd()),
+            ]);
+        }
+
         return $values;
     }
 }
diff --git a/tests/Invoice/Hydrator/InvoiceModelDefaultHydratorTest.php b/tests/Invoice/Hydrator/InvoiceModelDefaultHydratorTest.php
index 36fd8169..a3f4b468 100644
--- a/tests/Invoice/Hydrator/InvoiceModelDefaultHydratorTest.php
+++ b/tests/Invoice/Hydrator/InvoiceModelDefaultHydratorTest.php
@@ -45,6 +45,8 @@ class InvoiceModelDefaultHydratorTest extends TestCase
             'invoice.tax_plain',
             'invoice.total_time',
             'invoice.duration_decimal',
+            'invoice.first',
+            'invoice.last',
             'invoice.total',
             'invoice.total_nc',
             'invoice.total_plain',
diff --git a/tests/Invoice/Renderer/DebugRendererTest.php b/tests/Invoice/Renderer/DebugRendererTest.php
index 4365dfd3..55e1565a 100644
--- a/tests/Invoice/Renderer/DebugRendererTest.php
+++ b/tests/Invoice/Renderer/DebugRendererTest.php
@@ -72,6 +72,8 @@ class DebugRendererTest extends TestCase
         self::assertEquals($begin->format('m'), $data['model']['query.month_number']);
         self::assertEquals($begin->format('d'), $data['model']['query.day']);
         // TODO check values or formats?
+        self::assertEquals('2020.08.12', $data['model']['invoice.first']);
+        self::assertEquals('2022.10.23', $data['model']['invoice.last']);
     }
 
     protected function assertModelStructure(array $model, int $projectCounter = 0, int $activityCounter = 0)
@@ -89,6 +91,8 @@ class DebugRendererTest extends TestCase
             'invoice.tax_plain',
             'invoice.total_time',
             'invoice.duration_decimal',
+            'invoice.first',
+            'invoice.last',
             'invoice.total',
             'invoice.total_nc',
             'invoice.total_plain',
diff --git a/tests/Invoice/Renderer/RendererTestTrait.php b/tests/Invoice/Renderer/RendererTestTrait.php
index 5718bca2..dd1877a8 100644
--- a/tests/Invoice/Renderer/RendererTestTrait.php
+++ b/tests/Invoice/Renderer/RendererTestTrait.php
@@ -152,8 +152,8 @@ trait RendererTestTrait
             ->setUser($user2)
             ->setActivity($activity)
             ->setProject($project)
-            ->setBegin(new \DateTime())
-            ->setEnd(new \DateTime())
+            ->setBegin(new \DateTime('2020-08-13 14:00:00'))
+            ->setEnd(new \DateTime('2020-08-13 14:06:40'))
             ->setMetaField((new TimesheetMeta())->setName('foo-timesheet')->setValue('bar-timesheet'))
             ->setMetaField((new TimesheetMeta())->setName('foo-timesheet2')->setValue('bar-timesheet2')->setIsVisible(true))
         ;
@@ -166,8 +166,8 @@ trait RendererTestTrait
             ->setActivity($activity2)
             ->setDescription('== jhg ljhg ') // make sure that spreadsheets don't render it as formula
             ->setProject($project2)
-            ->setBegin(new \DateTime())
-            ->setEnd(new \DateTime())
+            ->setBegin(new \DateTime('2020-08-12 18:00:00'))
+            ->setEnd(new \DateTime('2020-08-12 18:30:00'))
             ->setMetaField((new TimesheetMeta())->setName('foo-timesheet')->setValue('bar-timesheet1')->setIsVisible(true))
         ;
 
@@ -198,8 +198,8 @@ trait RendererTestTrait
             ->setUser((new User())->setUsername('kevin'))
             ->setActivity($activity)
             ->setProject($project)
-            ->setBegin(new \DateTime())
-            ->setEnd(new \DateTime())
+            ->setBegin(new \DateTime('2021-03-12 07:13:00'))
+            ->setEnd(new \DateTime('2021-03-12 07:17:40'))
             ->setDescription(
                 "foo\n" .
                 "foo\r\n" .
@@ -291,8 +291,8 @@ trait RendererTestTrait
             ->setUser($user1)
             ->setActivity($activity)
             ->setProject($project)
-            ->setBegin(new \DateTime())
-            ->setEnd(new \DateTime())
+            ->setBegin(new \DateTime('2020-08-12 18:00:00'))
+            ->setEnd(new \DateTime('2022-10-23 18:30:00'))
         ;
 
         $entries = [$timesheet];