diff --git a/src/Form/Toolbar/AbstractToolbarForm.php b/src/Form/Toolbar/AbstractToolbarForm.php
index 5905a103..097de9d9 100644
--- a/src/Form/Toolbar/AbstractToolbarForm.php
+++ b/src/Form/Toolbar/AbstractToolbarForm.php
@@ -346,4 +346,13 @@ abstract class AbstractToolbarForm extends AbstractType
             ],
         ]);
     }
+
+    protected function addBillableChoice(FormBuilderInterface $builder)
+    {
+        $builder->add('billable', BillableType::class, [
+            'required' => false,
+            'placeholder' => null,
+            'search' => false,
+        ]);
+    }
 }
diff --git a/src/Form/Toolbar/BillableType.php b/src/Form/Toolbar/BillableType.php
new file mode 100644
index 00000000..4786fe78
--- /dev/null
+++ b/src/Form/Toolbar/BillableType.php
@@ -0,0 +1,40 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Form\Toolbar;
+
+use Symfony\Component\Form\AbstractType;
+use Symfony\Component\Form\Extension\Core\Type\ChoiceType;
+use Symfony\Component\OptionsResolver\OptionsResolver;
+
+class BillableType extends AbstractType
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function configureOptions(OptionsResolver $resolver)
+    {
+        $resolver->setDefaults([
+            'label' => 'label.billable',
+            'choices' => [
+                'entryState.all' => null,
+                'yes' => true,
+                'no' => false,
+            ],
+        ]);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getParent()
+    {
+        return ChoiceType::class;
+    }
+}
diff --git a/src/Form/Type/BillableType.php b/src/Form/Type/BillableType.php
new file mode 100644
index 00000000..d58db76e
--- /dev/null
+++ b/src/Form/Type/BillableType.php
@@ -0,0 +1,38 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Form\Type;
+
+use Symfony\Component\Form\AbstractType;
+use Symfony\Component\OptionsResolver\OptionsResolver;
+
+/**
+ * Custom form field type to select if something is billable.
+ * To be used in combination with the invoicing system.
+ */
+class BillableType extends AbstractType
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function configureOptions(OptionsResolver $resolver)
+    {
+        $resolver->setDefaults([
+            'label' => 'label.billable',
+        ]);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getParent()
+    {
+        return YesNoType::class;
+    }
+}
diff --git a/src/Repository/Query/BillableInterface.php b/src/Repository/Query/BillableInterface.php
new file mode 100644
index 00000000..87c4b031
--- /dev/null
+++ b/src/Repository/Query/BillableInterface.php
@@ -0,0 +1,48 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Repository\Query;
+
+interface BillableInterface
+{
+    /**
+     * Returns the internal value (null = ignore billable, true = is billable, false = is not billable).
+     *
+     * @return bool|null
+     */
+    public function getBillable(): ?bool;
+
+    /**
+     * Returns true if the billable flag should be used and should match true.
+     *
+     * @return bool
+     */
+    public function isBillable(): bool;
+
+    /**
+     * Returns true if the billable flag should be used and should match false.
+     *
+     * @return bool
+     */
+    public function isNotBillable(): bool;
+
+    /**
+     * Returns true if the billable flag should NOT be used.
+     *
+     * @return bool
+     */
+    public function isIgnoreBillable(): bool;
+
+    /**
+     * Pas null if you want to ignore the billable flag.
+     *
+     * @param bool|null $isBillable
+     */
+    public function setBillable(?bool $isBillable): void;
+}
diff --git a/src/Repository/Query/BillableTrait.php b/src/Repository/Query/BillableTrait.php
new file mode 100644
index 00000000..c00b1516
--- /dev/null
+++ b/src/Repository/Query/BillableTrait.php
@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * This file is part of the Kimai time-tracking app.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace App\Repository\Query;
+
+trait BillableTrait
+{
+    /**
+     * @var bool|null
+     */
+    private $billable = null;
+
+    public function getBillable(): ?bool
+    {
+        return $this->billable;
+    }
+
+    public function isBillable(): bool
+    {
+        return $this->billable === true;
+    }
+
+    public function isNotBillable(): bool
+    {
+        return $this->billable === false;
+    }
+
+    public function isIgnoreBillable(): bool
+    {
+        return $this->billable === null;
+    }
+
+    public function setBillable(?bool $isBillable): void
+    {
+        $this->billable = $isBillable;
+    }
+}
diff --git a/src/Repository/Query/InvoiceQuery.php b/src/Repository/Query/InvoiceQuery.php
index 750456ed..16a0099c 100644
--- a/src/Repository/Query/InvoiceQuery.php
+++ b/src/Repository/Query/InvoiceQuery.php
@@ -25,7 +25,7 @@ class InvoiceQuery extends TimesheetQuery
     public function __construct()
     {
         parent::__construct();
-        $this->setBillable(InvoiceQuery::STATE_BILLABLE);
+        $this->setBillable(true);
     }
 
     public function getTemplate(): ?InvoiceTemplate
diff --git a/src/Repository/Query/TimesheetQuery.php b/src/Repository/Query/TimesheetQuery.php
index cd60fa9b..7073f1a1 100644
--- a/src/Repository/Query/TimesheetQuery.php
+++ b/src/Repository/Query/TimesheetQuery.php
@@ -17,15 +17,15 @@ use App\Form\Model\DateRange;
 /**
  * Can be used for advanced timesheet repository queries.
  */
-class TimesheetQuery extends ActivityQuery
+class TimesheetQuery extends ActivityQuery implements BillableInterface
 {
+    use BillableTrait;
+
     public const STATE_ALL = 1;
     public const STATE_RUNNING = 2;
     public const STATE_STOPPED = 3;
     public const STATE_EXPORTED = 4;
     public const STATE_NOT_EXPORTED = 5;
-    public const STATE_BILLABLE = 6;
-    public const STATE_NOT_BILLABLE = 7;
 
     public const TIMESHEET_ORDER_ALLOWED = ['begin', 'end', 'duration', 'rate', 'customer', 'project', 'activity', 'description'];
 
@@ -45,10 +45,6 @@ class TimesheetQuery extends ActivityQuery
      * @var int
      */
     protected $exported = self::STATE_ALL;
-    /**
-     * @var int
-     */
-    private $billable = self::STATE_ALL;
     /**
      * @var \DateTime|null
      */
@@ -295,30 +291,6 @@ class TimesheetQuery extends ActivityQuery
         return $this;
     }
 
-    public function getBillable(): int
-    {
-        return $this->billable;
-    }
-
-    public function isBillable(): bool
-    {
-        return $this->billable === self::STATE_BILLABLE;
-    }
-
-    public function isNotBillable(): bool
-    {
-        return $this->billable === self::STATE_NOT_BILLABLE;
-    }
-
-    public function setBillable(int $billable): TimesheetQuery
-    {
-        if (\in_array($billable, [self::STATE_ALL, self::STATE_BILLABLE, self::STATE_NOT_BILLABLE], true)) {
-            $this->billable = $billable;
-        }
-
-        return $this;
-    }
-
     public function getModifiedAfter(): ?\DateTime
     {
         return $this->modifiedAfter;
diff --git a/tests/Repository/Query/InvoiceQueryTest.php b/tests/Repository/Query/InvoiceQueryTest.php
index 09158b31..7d7dfcd5 100644
--- a/tests/Repository/Query/InvoiceQueryTest.php
+++ b/tests/Repository/Query/InvoiceQueryTest.php
@@ -10,7 +10,6 @@
 namespace App\Tests\Repository\Query;
 
 use App\Repository\Query\InvoiceQuery;
-use App\Repository\Query\TimesheetQuery;
 
 /**
  * @covers \App\Repository\Query\InvoiceQuery
@@ -36,7 +35,11 @@ class InvoiceQueryTest extends TimesheetQueryTest
         $this->assertMarkAsExported($sut);
         $this->assertModifiedAfter($sut);
 
-        self::assertEquals(TimesheetQuery::STATE_BILLABLE, $sut->getBillable());
+        self::assertTrue($sut->getBillable());
+        self::assertTrue($sut->isBillable());
+        self::assertFalse($sut->isNotBillable());
+        self::assertFalse($sut->isIgnoreBillable());
+
         self::assertTrue($sut->isBillable());
         self::assertFalse($sut->isNotBillable());
         $this->assertBillable($sut);
diff --git a/tests/Repository/Query/TimesheetQueryTest.php b/tests/Repository/Query/TimesheetQueryTest.php
index 26c4a1f6..9b4656e9 100644
--- a/tests/Repository/Query/TimesheetQueryTest.php
+++ b/tests/Repository/Query/TimesheetQueryTest.php
@@ -37,7 +37,11 @@ class TimesheetQueryTest extends BaseQueryTest
         $this->assertSearchTerm($sut);
         $this->assertModifiedAfter($sut);
 
-        self::assertEquals(TimesheetQuery::STATE_ALL, $sut->getBillable());
+        self::assertNull($sut->getBillable());
+        self::assertFalse($sut->isBillable());
+        self::assertFalse($sut->isNotBillable());
+        self::assertTrue($sut->isIgnoreBillable());
+
         self::assertFalse($sut->isBillable());
         self::assertFalse($sut->isNotBillable());
         $this->assertBillable($sut);
@@ -140,22 +144,22 @@ class TimesheetQueryTest extends BaseQueryTest
 
     protected function assertBillable(TimesheetQuery $sut)
     {
-        self::assertInstanceOf(TimesheetQuery::class, $sut->setBillable(TimesheetQuery::STATE_ALL));
-        self::assertEquals(TimesheetQuery::STATE_ALL, $sut->getBillable());
+        $sut->setBillable(null);
+        self::assertNull($sut->getBillable());
         self::assertFalse($sut->isBillable());
         self::assertFalse($sut->isNotBillable());
+        self::assertTrue($sut->isIgnoreBillable());
 
-        $sut->setBillable(PHP_INT_MAX);
-        self::assertEquals(TimesheetQuery::STATE_ALL, $sut->getBillable());
-
-        $sut->setBillable(TimesheetQuery::STATE_BILLABLE);
-        self::assertEquals(TimesheetQuery::STATE_BILLABLE, $sut->getBillable());
+        $sut->setBillable(true);
+        self::assertTrue($sut->getBillable());
         self::assertTrue($sut->isBillable());
         self::assertFalse($sut->isNotBillable());
+        self::assertFalse($sut->isIgnoreBillable());
 
-        $sut->setBillable(TimesheetQuery::STATE_NOT_BILLABLE);
-        self::assertEquals(TimesheetQuery::STATE_NOT_BILLABLE, $sut->getBillable());
+        $sut->setBillable(false);
+        self::assertFalse($sut->getBillable());
         self::assertFalse($sut->isBillable());
         self::assertTrue($sut->isNotBillable());
+        self::assertFalse($sut->isIgnoreBillable());
     }
 }
diff --git a/translations/messages.de.xlf b/translations/messages.de.xlf
index 18bb061e..0c17479f 100644
--- a/translations/messages.de.xlf
+++ b/translations/messages.de.xlf
@@ -340,6 +340,10 @@
                 <source>placeholder.type_message</source>
                 <target>Schreibe Deine Nachricht...</target>
             </trans-unit>
+            <trans-unit id="label.billable">
+                <source>label.billable</source>
+                <target>Abrechenbar</target>
+            </trans-unit>
 
             <!--
               Buttons & Actions
diff --git a/translations/messages.en.xlf b/translations/messages.en.xlf
index aae0e882..d6c3e96e 100644
--- a/translations/messages.en.xlf
+++ b/translations/messages.en.xlf
@@ -340,6 +340,10 @@
                 <source>placeholder.type_message</source>
                 <target>Type your message...</target>
             </trans-unit>
+            <trans-unit id="label.billable">
+                <source>label.billable</source>
+                <target>Billable</target>
+            </trans-unit>
 
             <!--
               Buttons & Actions
diff --git a/translations/messages.he.xlf b/translations/messages.he.xlf
index 4c78b026..53dd4369 100644
--- a/translations/messages.he.xlf
+++ b/translations/messages.he.xlf
@@ -312,6 +312,10 @@
         <source>label.create_more</source>
         <target>צור רשומות נוספות</target>
       </trans-unit>
+      <trans-unit id="label.billable">
+        <source>label.billable</source>
+        <target>להחזר</target>
+      </trans-unit>
       <trans-unit id="zldXQq6" resname="label.actions">
         <source>label.actions</source>
         <target>פעולות</target>