diff --git a/.ci/php-cs-fixer/.php-cs-fixer.php b/.ci/php-cs-fixer/.php-cs-fixer.php
index 7d1335ce92..7475d96d5e 100644
--- a/.ci/php-cs-fixer/.php-cs-fixer.php
+++ b/.ci/php-cs-fixer/.php-cs-fixer.php
@@ -58,5 +58,6 @@ return $config->setRules([
                              'type_declaration_spaces'       => false,
                              'cast_spaces'                   => false,
                              'binary_operator_spaces'        => false,
+                             'void_return'                   => true,
                          ])
               ->setFinder($finder);
diff --git a/app/Api/V1/Requests/Data/Bulk/MoveTransactionsRequest.php b/app/Api/V1/Requests/Data/Bulk/MoveTransactionsRequest.php
index d1447d9b85..bcd0cb019c 100644
--- a/app/Api/V1/Requests/Data/Bulk/MoveTransactionsRequest.php
+++ b/app/Api/V1/Requests/Data/Bulk/MoveTransactionsRequest.php
@@ -66,7 +66,7 @@ class MoveTransactionsRequest extends FormRequest
     public function withValidator(Validator $validator): void
     {
         $validator->after(
-            function (Validator $validator) {
+            function (Validator $validator): void {
                 // validate start before end only if both are there.
                 $data = $validator->getData();
                 if (array_key_exists('original_account', $data) && array_key_exists('destination_account', $data)) {
diff --git a/app/Api/V1/Requests/Data/Bulk/TransactionRequest.php b/app/Api/V1/Requests/Data/Bulk/TransactionRequest.php
index fa164daa11..0ef3692397 100644
--- a/app/Api/V1/Requests/Data/Bulk/TransactionRequest.php
+++ b/app/Api/V1/Requests/Data/Bulk/TransactionRequest.php
@@ -67,7 +67,7 @@ class TransactionRequest extends FormRequest
     public function withValidator(Validator $validator): void
     {
         $validator->after(
-            function (Validator $validator) {
+            function (Validator $validator): void {
                 // validate transaction query data.
                 $this->validateTransactionQuery($validator);
             }
diff --git a/app/Api/V1/Requests/Models/AvailableBudget/Request.php b/app/Api/V1/Requests/Models/AvailableBudget/Request.php
index c65ec4bda9..1bbee10c3a 100644
--- a/app/Api/V1/Requests/Models/AvailableBudget/Request.php
+++ b/app/Api/V1/Requests/Models/AvailableBudget/Request.php
@@ -74,7 +74,7 @@ class Request extends FormRequest
     public function withValidator(Validator $validator): void
     {
         $validator->after(
-            static function (Validator $validator) {
+            static function (Validator $validator): void {
                 // validate start before end only if both are there.
                 $data = $validator->getData();
                 if (array_key_exists('start', $data) && array_key_exists('end', $data)) {
diff --git a/app/Api/V1/Requests/Models/Bill/StoreRequest.php b/app/Api/V1/Requests/Models/Bill/StoreRequest.php
index eb6d78cac5..41c0bf0c4a 100644
--- a/app/Api/V1/Requests/Models/Bill/StoreRequest.php
+++ b/app/Api/V1/Requests/Models/Bill/StoreRequest.php
@@ -92,7 +92,7 @@ class StoreRequest extends FormRequest
     public function withValidator(Validator $validator): void
     {
         $validator->after(
-            static function (Validator $validator) {
+            static function (Validator $validator): void {
                 $data = $validator->getData();
                 $min  = (string)($data['amount_min'] ?? '0');
                 $max  = (string)($data['amount_max'] ?? '0');
diff --git a/app/Api/V1/Requests/Models/Bill/UpdateRequest.php b/app/Api/V1/Requests/Models/Bill/UpdateRequest.php
index b29dfbdec1..fe7e1dc543 100644
--- a/app/Api/V1/Requests/Models/Bill/UpdateRequest.php
+++ b/app/Api/V1/Requests/Models/Bill/UpdateRequest.php
@@ -95,7 +95,7 @@ class UpdateRequest extends FormRequest
     public function withValidator(Validator $validator): void
     {
         $validator->after(
-            static function (Validator $validator) {
+            static function (Validator $validator): void {
                 $data = $validator->getData();
                 if (array_key_exists('amount_min', $data) && array_key_exists('amount_max', $data)) {
                     $min = $data['amount_min'] ?? '0';
diff --git a/app/Console/Commands/Correction/FixAccountTypes.php b/app/Console/Commands/Correction/FixAccountTypes.php
index 95056cd08e..fc57bef16a 100644
--- a/app/Console/Commands/Correction/FixAccountTypes.php
+++ b/app/Console/Commands/Correction/FixAccountTypes.php
@@ -51,7 +51,7 @@ class FixAccountTypes extends Command
     /**
      * Execute the console command.
      *
-     * @throws FireflyException|\JsonException
+     * @throws FireflyException
      */
     public function handle(): int
     {
@@ -373,7 +373,7 @@ class FixAccountTypes extends Command
         $this->inspectJournal($journal);
     }
 
-    private function giveNewExpense(TransactionJournal $journal, Transaction $destination)
+    private function giveNewExpense(TransactionJournal $journal, Transaction $destination): void
     {
         app('log')->debug(sprintf('An account of type "%s" could be a valid destination.', AccountTypeEnum::EXPENSE->value));
         $this->factory->setUser($journal->user);
diff --git a/app/Console/Commands/System/ForceDecimalSize.php b/app/Console/Commands/System/ForceDecimalSize.php
index 5a60be307b..97ddaa3c72 100644
--- a/app/Console/Commands/System/ForceDecimalSize.php
+++ b/app/Console/Commands/System/ForceDecimalSize.php
@@ -374,7 +374,7 @@ class ForceDecimalSize extends Command
     /**
      * This method fixes all piggy bank repetitions in currency $currency.
      */
-    private function correctPiggyRepetitionAmounts(TransactionCurrency $currency, array $fields)
+    private function correctPiggyRepetitionAmounts(TransactionCurrency $currency, array $fields): void
     {
         $operator          = $this->operator;
         $cast              = $this->cast;
diff --git a/app/Console/Commands/Upgrade/UpgradeCurrencyPreferences.php b/app/Console/Commands/Upgrade/UpgradeCurrencyPreferences.php
index e36ea0b2e9..5e8b6d48be 100644
--- a/app/Console/Commands/Upgrade/UpgradeCurrencyPreferences.php
+++ b/app/Console/Commands/Upgrade/UpgradeCurrencyPreferences.php
@@ -91,7 +91,7 @@ class UpgradeCurrencyPreferences extends Command
         }
     }
 
-    private function upgradeGroupPreferences(UserGroup $group)
+    private function upgradeGroupPreferences(UserGroup $group): void
     {
         $currencies = TransactionCurrency::get();
         $enabled    = new Collection();
diff --git a/app/Generator/Webhook/StandardMessageGenerator.php b/app/Generator/Webhook/StandardMessageGenerator.php
index 1aa4ad4db7..2ac1846f43 100644
--- a/app/Generator/Webhook/StandardMessageGenerator.php
+++ b/app/Generator/Webhook/StandardMessageGenerator.php
@@ -180,6 +180,7 @@ class StandardMessageGenerator implements MessageGeneratorInterface
                 break;
 
             case WebhookResponse::TRANSACTIONS->value:
+                /** @var TransactionGroup $model */
                 $transformer = new TransactionGroupTransformer();
 
                 try {
@@ -196,6 +197,7 @@ class StandardMessageGenerator implements MessageGeneratorInterface
                 break;
 
             case WebhookResponse::ACCOUNTS->value:
+                /** @var TransactionGroup $model */
                 $accounts = $this->collectAccounts($model);
                 foreach ($accounts as $account) {
                     $transformer = new AccountTransformer();
diff --git a/app/Http/Controllers/Auth/LoginController.php b/app/Http/Controllers/Auth/LoginController.php
index 34c3af6ead..3882757b4b 100644
--- a/app/Http/Controllers/Auth/LoginController.php
+++ b/app/Http/Controllers/Auth/LoginController.php
@@ -222,7 +222,7 @@ class LoginController extends Controller
      *
      * @throws ValidationException
      */
-    protected function sendFailedLoginResponse(Request $request)
+    protected function sendFailedLoginResponse(Request $request): void
     {
         $exception             = ValidationException::withMessages(
             [
diff --git a/app/TransactionRules/Actions/ConvertToDeposit.php b/app/TransactionRules/Actions/ConvertToDeposit.php
index b1e6b0dce1..d866262ec3 100644
--- a/app/TransactionRules/Actions/ConvertToDeposit.php
+++ b/app/TransactionRules/Actions/ConvertToDeposit.php
@@ -83,7 +83,7 @@ class ConvertToDeposit implements ActionInterface
 
             try {
                 $res = $this->convertWithdrawalArray($object);
-            } catch (FireflyException|\JsonException $e) {
+            } catch (FireflyException $e) {
                 app('log')->debug('Could not convert withdrawal to deposit.');
                 app('log')->error($e->getMessage());
                 event(new RuleActionFailedOnArray($this->action, $journal, trans('rules.complex_error')));
@@ -100,7 +100,7 @@ class ConvertToDeposit implements ActionInterface
 
             try {
                 $res = $this->convertTransferArray($object);
-            } catch (FireflyException|\JsonException $e) {
+            } catch (FireflyException $e) {
                 app('log')->debug('Could not convert transfer to deposit.');
                 app('log')->error($e->getMessage());
                 event(new RuleActionFailedOnArray($this->action, $journal, trans('rules.complex_error')));
diff --git a/app/TransactionRules/Actions/ConvertToWithdrawal.php b/app/TransactionRules/Actions/ConvertToWithdrawal.php
index 648b34cf0d..1a68b48a34 100644
--- a/app/TransactionRules/Actions/ConvertToWithdrawal.php
+++ b/app/TransactionRules/Actions/ConvertToWithdrawal.php
@@ -86,7 +86,7 @@ class ConvertToWithdrawal implements ActionInterface
 
             try {
                 $res = $this->convertDepositArray($object);
-            } catch (FireflyException|\JsonException $e) {
+            } catch (FireflyException $e) {
                 app('log')->debug('Could not convert transfer to deposit.');
                 app('log')->error($e->getMessage());
                 event(new RuleActionFailedOnArray($this->action, $journal, trans('rules.complex_error')));
@@ -102,7 +102,7 @@ class ConvertToWithdrawal implements ActionInterface
 
         try {
             $res = $this->convertTransferArray($object);
-        } catch (FireflyException|\JsonException $e) {
+        } catch (FireflyException $e) {
             app('log')->debug('Could not convert transfer to deposit.');
             app('log')->error($e->getMessage());
             event(new RuleActionFailedOnArray($this->action, $journal, trans('rules.complex_error')));
diff --git a/app/User.php b/app/User.php
index 529019fc18..957f8fc788 100644
--- a/app/User.php
+++ b/app/User.php
@@ -527,7 +527,7 @@ class User extends Authenticatable
      *
      * @deprecated
      */
-    public function setLdapDomain($domain)
+    public function setLdapDomain($domain): void
     {
         $this->{$this->getLdapDomainColumn()} = $domain;
     }
@@ -539,7 +539,7 @@ class User extends Authenticatable
      *
      * @deprecated
      */
-    public function setLdapGuid($guid)
+    public function setLdapGuid($guid): void
     {
         $this->{$this->getLdapGuidColumn()} = $guid;
     }