diff --git a/src/DataFixtures/InstrumentFixture.php b/src/DataFixtures/InstrumentFixture.php
index ede3a27..c66ef99 100644
--- a/src/DataFixtures/InstrumentFixture.php
+++ b/src/DataFixtures/InstrumentFixture.php
@@ -30,6 +30,7 @@ public function load(ObjectManager $manager): void
         $appl_inst->setEusipa(Instrument::EUSIPA_KNOCKOUT);
         $appl_inst->setCurrency("EUR");
         $appl_inst->setUnderlying($appl);
+        $appl_inst->setExecutionTaxRate(0.0012); // 0.12 %
         $manager->persist($appl_inst);
 
         $appl_terms = new InstrumentTerms();
@@ -48,6 +49,7 @@ public function load(ObjectManager $manager): void
         $msft_inst->setEusipa(Instrument::EUSIPA_UNDERLYING);
         $msft_inst->setCurrency("USD");
         $msft_inst->setUnderlying($msft);
+        $appl_inst->setExecutionTaxRate(0.0035); // 0.35 %
         $manager->persist($msft_inst);
 
         $manager->flush();
diff --git a/src/Entity/Instrument.php b/src/Entity/Instrument.php
index 45676cf..6f455ce 100644
--- a/src/Entity/Instrument.php
+++ b/src/Entity/Instrument.php
@@ -106,6 +106,10 @@ class Instrument
     #[ORM\Column(type: "text", length: 50000, nullable: true)]
     private $notes;
 
+    #[ORM\Column(type: "decimal", precision: 5, scale: 4, nullable: true, options: ["unsigned" => true])]
+    #[Assert\Range(min: 0, max: 1)]
+    private $executionTaxRate;
+
     public function getId(): ?int
     {
         return $this->id;
@@ -200,6 +204,18 @@ public function setNotes(?string $notes): self
         return $this;
     }
 
+    public function getExecutionTaxRate(): ?string
+    {
+        return $this->executionTaxRate;
+    }
+
+    public function setExecutionTaxRate(?string $executionTaxRate): self
+    {
+        $this->executionTaxRate = $executionTaxRate;
+
+        return $this;
+    }
+
     public function getUnderlying(): ?Asset
     {
         return $this->underlying;
diff --git a/src/Form/ExecutionType.php b/src/Form/ExecutionType.php
index cc1bd1b..b72d3ee 100644
--- a/src/Form/ExecutionType.php
+++ b/src/Form/ExecutionType.php
@@ -62,6 +62,8 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
         $user = $this->token->getToken()->getUser();
 
         if ($data->instrument) {
+            $executionTaxRate = $data->instrument->getExecutionTaxRate();
+            $direction = $data->instrument->getDirection();
             $builder->add('instrument', TextType::class, ['disabled' =>'true']);
         } else {
             $builder->add('instrument', EntityType::class, ['class' => Instrument::class]);
@@ -109,7 +111,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             ->add('execution_id', NumberType::class, ['label' => 'Execution ID', 'html5' => true, 'required' => false, 'help' => 'Execution ID used by the broker'])
             ->add('marketplace', TextType::class, ['required' => false, 'help' => 'Location of the exchange'])
             ->add('commission', MoneyType::class, ['required' => false, 'html5' => false, 'currency' => $currency, 'scale' => 4, 'help' => 'Commission cost (negative amount)'])
-            ->add('tax', MoneyType::class, ['required' => false, 'html5' => false, 'currency' => $currency, 'scale' => 4, 'help' => 'paid tax is negative, refunded tax positive'])
+            ->add('tax', MoneyType::class, ['required' => false, 'html5' => false, 'currency' => $currency, 'scale' => 4, 'help' => 'Paid tax is negative, refunded tax positive' . (!empty($executionTaxRate) && !empty($direction) ? ' (applying execution tax rate of -' . $executionTaxRate * 100 . '% when empty)'  : '')])
             ->add('interest', MoneyType::class, ['required' => false, 'html5' => false, 'currency' => $currency, 'scale' => 4, 'help' => 'Paid interest (negative amount)'])
             ->add('notes', TextareaType::class, ['required' => false])
             ->add('consolidated', CheckboxType::class, ['required' => false, 'help' => 'Check if this transaction matches with your broker'])
diff --git a/src/Form/InstrumentType.php b/src/Form/InstrumentType.php
index 50de485..4f2525f 100644
--- a/src/Form/InstrumentType.php
+++ b/src/Form/InstrumentType.php
@@ -14,6 +14,7 @@
 use Symfony\Component\Form\Extension\Core\Type\ResetType;
 use Symfony\Component\Form\Extension\Core\Type\SubmitType;
 use Symfony\Component\Form\Extension\Core\Type\TextType;
+use Symfony\Component\Form\Extension\Core\Type\MoneyType;
 use Symfony\Component\Form\Extension\Core\Type\TextareaType;
 use Symfony\Component\Form\Extension\Core\Type\UrlType;
 use Symfony\Component\OptionsResolver\OptionsResolver;
@@ -89,6 +90,7 @@ public function buildForm(FormBuilderInterface $builder, array $options): void
             ->add('terminationdate', DateType::class, ['required' => false, 'label'=>'Termination date', 'widget' => 'single_text'])
             ->add('url', UrlType::class, ['required' => false, 'label' => 'Instrument website'])
             ->add('notes', TextareaType::class, ['required' => false])
+            ->add('executiontaxrate', TextType::class, ['required' => false, 'label'=>'Execution tax rate %', 'help' => 'Tax rate percentage applicable to executed trades (e.g. 0.12% is 0.0012)'])
             ->add('save', SubmitType::class, ['label' => 'Submit', 'attr' => ['class' => 'btn btn-primary']])
             ->add('reset', ResetType::class, ['label' => 'Reset', 'attr' => ['class' => 'btn btn-secondary']])
             ->add('back', ButtonType::class, ['label' => 'Back', 'attr' => ['class' => 'btn btn-secondary']])
diff --git a/src/Form/Model/ExecutionFormModel.php b/src/Form/Model/ExecutionFormModel.php
index 3551e80..5124f88 100644
--- a/src/Form/Model/ExecutionFormModel.php
+++ b/src/Form/Model/ExecutionFormModel.php
@@ -102,8 +102,11 @@ private function populateTransaction(Transaction $transaction)
         } else {
             $transaction->setCommission(null);
         }
-        if ($this->tax) {
+        if ($this->tax !== null) {
             $transaction->setTax($this->tax);
+        } elseif($this->instrument->getExecutionTaxRate() != null && $this->direction != 0 && isset($total)) {
+            // apply execution tax rate of the instrument if no tax provided in the tax field
+            $transaction->setTax($this->direction * $total * $this->instrument->getExecutionTaxRate());
         } else {
             $transaction->setTax(null);
         }
diff --git a/templates/instrument/edit.html.twig b/templates/instrument/edit.html.twig
index 806fc8a..61554a7 100644
--- a/templates/instrument/edit.html.twig
+++ b/templates/instrument/edit.html.twig
@@ -19,6 +19,7 @@
   <div class="col-md-6">{{ form_row(form.issuer) }}</div>
   <div class="col-md-6">{{ form_row(form.url) }}</div>
   <div class="col-12">{{ form_row(form.notes) }}</div>
+  <div class="col-md-4">{{ form_row(form.executiontaxrate) }}</div>
 </div>
 
 <div>{{ form_errors(form) }}</div>
diff --git a/tests/ExecutionFormModelTest.php b/tests/ExecutionFormModelTest.php
index de6b9b0..777c34e 100644
--- a/tests/ExecutionFormModelTest.php
+++ b/tests/ExecutionFormModelTest.php
@@ -3,6 +3,7 @@
 namespace App\Tests;
 
 use App\Entity\Execution;
+use App\Entity\Instrument;
 use App\Entity\Transaction;
 use App\Form\Model\ExecutionFormModel;
 use PHPUnit\Framework\TestCase;
@@ -45,4 +46,57 @@ public function testRoundtrip(): void
         $this->assertSame($transaction2->getCommission(), $transaction->getCommission());
         $this->assertSame($transaction2->getInterest(), $transaction->getInterest());
     }
+    
+    public function testTaxCalculation(): void
+    {
+        $execution = new Execution();
+        $transaction = new Transaction();
+        $instrument = new Instrument();
+        $execution->setTransaction($transaction);
+        $execution->setInstrument($instrument);
+        $instrument->setExecutionTaxRate(0.0012); // 0.12 %
+
+        $transaction->setTime(new \DateTime());
+        $execution->setPrice(123);
+        $execution->setVolume(15);
+        $execution->setCurrency("EUR");
+
+        // should keep tax 0
+        $transaction->setTax(0);
+        $data = new ExecutionFormModel();
+        $data->fromExecution($execution);
+        $data->populateExecution($execution);
+        $this->assertSame($transaction->getTax(), strval(0));
+
+        // should keep the inserted tax value
+        $transaction->setTax(-1.23);
+        $data = new ExecutionFormModel();
+        $data->fromExecution($execution);
+        $data->populateExecution($execution);
+        $this->assertSame($transaction->getTax(), strval(-1.23));
+
+        // should add calculated tax (open)
+        $calculatedTax = is_numeric($transaction->getPortfolio()) && is_numeric($execution->getInstrument()->getExecutionTaxRate()) ? $transaction->getPortfolio() * $execution->getInstrument()->getExecutionTaxRate() : null; // -1845 * 0.0012 = '-2.214'
+        $transaction->setTax(null);
+        $data = new ExecutionFormModel();
+        $data->fromExecution($execution);
+        $data->populateExecution($execution);
+        $this->assertSame($transaction->getTax(), strval($calculatedTax));
+
+        // should add calculated tax (close)
+        $transaction->setTax(null);
+        $execution->setDirection(-1);
+        $data = new ExecutionFormModel();
+        $data->fromExecution($execution);
+        $data->populateExecution($execution);
+        $this->assertSame($transaction->getTax(), strval($calculatedTax));
+
+        // should add calculated tax (neutral)
+        $transaction->setTax(null);
+        $execution->setDirection(0);
+        $data = new ExecutionFormModel();
+        $data->fromExecution($execution);
+        $data->populateExecution($execution);
+        $this->assertSame($transaction->getTax(), null);
+    }
 }