diff --git a/app/Validation/Account/DepositValidation.php b/app/Validation/Account/DepositValidation.php
index 17bd46b676..f78f74dfae 100644
--- a/app/Validation/Account/DepositValidation.php
+++ b/app/Validation/Account/DepositValidation.php
@@ -70,7 +70,7 @@ trait DepositValidation
             }
             if (null !== $search) {
                 Log::debug(sprintf('findExistingAccount() returned #%d ("%s"), so the result is true.', $search->id, $search->name));
-                $this->destination = $search;
+                $this->setDestination($search);
                 $result            = true;
             }
         }
@@ -107,7 +107,7 @@ trait DepositValidation
         $accountNumber = array_key_exists('number', $array) ? $array['number'] : null;
         Log::debug('Now in validateDepositSource', $array);
 
-        // null = we found nothing at all or didnt even search
+        // null = we found nothing at all or didn't even search
         // false = invalid results
         $result = null;
 
@@ -129,6 +129,11 @@ trait DepositValidation
                 Log::debug(sprintf('User submitted an ID (#%d), which is a "%s", so this is not a valid source.', $accountId, $search->accountType->type));
                 Log::debug(sprintf('Firefly III accepts ID #%d as valid account data.', $accountId));
             }
+            if (null !== $search && in_array($search->accountType->type, $validTypes, true)) {
+                Log::debug('ID result is not null and seems valid, save as source account.');
+                $this->setSource($search);
+                $result       = true;
+            }
         }
 
         // if user submits an IBAN:
@@ -138,10 +143,15 @@ trait DepositValidation
                 Log::debug(sprintf('User submitted IBAN ("%s"), which is a "%s", so this is not a valid source.', $accountIban, $search->accountType->type));
                 $result = false;
             }
+            if (null !== $search && in_array($search->accountType->type, $validTypes, true)) {
+                Log::debug('IBAN result is not null and seems valid, save as source account.');
+                $this->setSource($search);
+                $result       = true;
+            }
         }
 
         // if user submits a number:
-        if (null !== $accountNumber) {
+        if (null !== $accountNumber && '' !== $accountNumber) {
             $search = $this->accountRepository->findByAccountNumber($accountNumber, $validTypes);
             if (null !== $search && !in_array($search->accountType->type, $validTypes, true)) {
                 Log::debug(
@@ -149,6 +159,11 @@ trait DepositValidation
                 );
                 $result = false;
             }
+            if (null !== $search && in_array($search->accountType->type, $validTypes, true)) {
+                Log::debug('Number result is not null and seems valid, save as source account.');
+                $this->setSource($search);
+                $result       = true;
+            }
         }
 
         // if the account can be created anyway we don't need to search.
@@ -159,7 +174,7 @@ trait DepositValidation
             $account              = new Account();
             $accountType          = AccountType::whereType(AccountType::REVENUE)->first();
             $account->accountType = $accountType;
-            $this->source         = $account;
+            $this->setSource($account);
         }
 
         return $result ?? false;
diff --git a/app/Validation/Account/LiabilityValidation.php b/app/Validation/Account/LiabilityValidation.php
index feb8c155dc..805271f1ba 100644
--- a/app/Validation/Account/LiabilityValidation.php
+++ b/app/Validation/Account/LiabilityValidation.php
@@ -91,7 +91,7 @@ trait LiabilityValidation
                 return false;
             }
             Log::debug(sprintf('Return true, found #%d ("%s")', $result->id, $result->name));
-            $this->source = $result;
+            $this->setSource($result);
             return true;
         }
 
@@ -109,7 +109,7 @@ trait LiabilityValidation
             $account              = new Account();
             $accountType          = AccountType::whereType(AccountType::LIABILITY_CREDIT)->first();
             $account->accountType = $accountType;
-            $this->source         = $account;
+            $this->setSource($account);
         }
 
         return $result;
diff --git a/app/Validation/Account/OBValidation.php b/app/Validation/Account/OBValidation.php
index 9f738c7b6c..1f1e349b27 100644
--- a/app/Validation/Account/OBValidation.php
+++ b/app/Validation/Account/OBValidation.php
@@ -70,7 +70,7 @@ trait OBValidation
             }
             if (null !== $search) {
                 Log::debug(sprintf('findExistingAccount() returned #%d ("%s"), so the result is true.', $search->id, $search->name));
-                $this->destination = $search;
+                $this->setDestination($search);
                 $result            = true;
             }
         }
@@ -127,7 +127,7 @@ trait OBValidation
             // the source resulted in an account, AND it's of a valid type.
             if (null !== $search && in_array($search->accountType->type, $validTypes, true)) {
                 Log::debug(sprintf('Found account of correct type: #%d, "%s"', $search->id, $search->name));
-                $this->source = $search;
+                $this->setSource($search);
                 $result       = true;
             }
         }
@@ -141,7 +141,7 @@ trait OBValidation
             $account              = new Account();
             $accountType          = AccountType::whereType(AccountType::INITIAL_BALANCE)->first();
             $account->accountType = $accountType;
-            $this->source         = $account;
+            $this->setSource($account);
         }
 
         return $result ?? false;
diff --git a/app/Validation/Account/ReconciliationValidation.php b/app/Validation/Account/ReconciliationValidation.php
index f964a01585..1277b76fa3 100644
--- a/app/Validation/Account/ReconciliationValidation.php
+++ b/app/Validation/Account/ReconciliationValidation.php
@@ -64,7 +64,7 @@ trait ReconciliationValidation
 
             return false;
         }
-        $this->source = $search;
+        $this->setSource($search);
         Log::debug('Valid source account!');
 
         return true;
@@ -85,7 +85,7 @@ trait ReconciliationValidation
         // source to the asset account that is the destination.
         if (null === $accountId && null === $accountName) {
             Log::debug('The source is valid because ID and name are NULL.');
-            $this->source = new Account();
+            $this->setSource(new Account());
             return true;
         }
 
@@ -101,7 +101,7 @@ trait ReconciliationValidation
 
             return false;
         }
-        $this->source = $search;
+        $this->setSource($search);
         Log::debug('Valid source account!');
 
         return true;
diff --git a/app/Validation/Account/TransferValidation.php b/app/Validation/Account/TransferValidation.php
index 9daa1c7bf4..e8032e7428 100644
--- a/app/Validation/Account/TransferValidation.php
+++ b/app/Validation/Account/TransferValidation.php
@@ -59,7 +59,7 @@ trait TransferValidation
 
             return false;
         }
-        $this->destination = $search;
+        $this->setDestination($search);
 
         // must not be the same as the source account
         if (null !== $this->source && $this->source->id === $this->destination->id) {
@@ -116,7 +116,7 @@ trait TransferValidation
 
             return false;
         }
-        $this->source = $search;
+        $this->setSource($search);
         Log::debug('Valid source!');
 
         return true;
diff --git a/app/Validation/Account/WithdrawalValidation.php b/app/Validation/Account/WithdrawalValidation.php
index 191f03087b..54af2768ee 100644
--- a/app/Validation/Account/WithdrawalValidation.php
+++ b/app/Validation/Account/WithdrawalValidation.php
@@ -61,7 +61,7 @@ trait WithdrawalValidation
 
             return false;
         }
-        $this->source = $search;
+        $this->setSource($search);
         Log::debug('Valid source account!');
 
         return true;
@@ -108,7 +108,7 @@ trait WithdrawalValidation
             if (null !== $found) {
                 $type = $found->accountType->type;
                 if (in_array($type, $validTypes, true)) {
-                    $this->destination = $found;
+                    $this->setDestination($found);
                     return true;
                 }
                 $this->destError = (string)trans('validation.withdrawal_dest_bad_data', ['id' => $accountId, 'name' => $accountName]);
@@ -151,7 +151,7 @@ trait WithdrawalValidation
 
             return false;
         }
-        $this->source = $search;
+        $this->setSource($search);
         Log::debug('Valid source account!');
 
         return true;
diff --git a/app/Validation/AccountValidator.php b/app/Validation/AccountValidator.php
index a91ad2c261..f5cc6880fd 100644
--- a/app/Validation/AccountValidator.php
+++ b/app/Validation/AccountValidator.php
@@ -264,4 +264,34 @@ class AccountValidator
 
         return null;
     }
+
+    /**
+     * @param  Account|null  $account
+     */
+    public function setDestination(?Account $account): void
+    {
+        if(null === $account) {
+            Log::debug('AccountValidator destination is set to NULL');
+        }
+        if(null !== $account) {
+            Log::debug(sprintf('AccountValidator destination is set to #%d: "%s" (%s)', $account->id, $account->name, $account?->accountType->type));
+        }
+        $this->destination = $account;
+    }
+
+    /**
+     * @param  Account|null  $account
+     */
+    public function setSource(?Account $account): void
+    {
+        if(null === $account) {
+            Log::debug('AccountValidator source is set to NULL');
+        }
+        if(null !== $account) {
+            Log::debug(sprintf('AccountValidator source is set to #%d: "%s" (%s)', $account->id, $account->name, $account?->accountType->type));
+        }
+        $this->source = $account;
+    }
+
+
 }
diff --git a/app/Validation/TransactionValidation.php b/app/Validation/TransactionValidation.php
index e89c0f0b41..63c98c4eec 100644
--- a/app/Validation/TransactionValidation.php
+++ b/app/Validation/TransactionValidation.php
@@ -24,10 +24,12 @@ declare(strict_types=1);
 namespace FireflyIII\Validation;
 
 use FireflyIII\Models\Account;
+use FireflyIII\Models\AccountType;
 use FireflyIII\Models\Transaction;
 use FireflyIII\Models\TransactionGroup;
 use FireflyIII\Models\TransactionJournal;
 use FireflyIII\Models\TransactionType;
+use FireflyIII\Repositories\Account\AccountRepositoryInterface;
 use Illuminate\Validation\Validator;
 use Log;
 
@@ -143,25 +145,133 @@ trait TransactionValidation
         // sanity check for reconciliation accounts. They can't both be null.
         $this->sanityCheckReconciliation($validator, $transactionType, $index, $source, $destination);
 
-        // deposit and the source is a liability or an asset account with a different
-        // currency than submitted? then the foreign currency info must be present as well (and filled in).
-        if (0 === $validator->errors()->count() && null !== $accountValidator->source && TransactionType::DEPOSIT === ucfirst($transactionType)) {
-            $accountType = $accountValidator?->source?->accountType?->type;
-            if (in_array($accountType, config('firefly.valid_currency_account_types'), true) && !$this->hasForeignCurrencyInfo($transaction)) {
-                $validator->errors()->add(sprintf('transactions.%d.foreign_amount', $index), (string)trans('validation.require_foreign_currency'));
-            }
+        // sanity check for currency information.
+        $this->sanityCheckForeignCurrency($validator, $accountValidator, $transaction, $transactionType, $index);
+    }
+
+    /**
+     * TODO describe this method.
+     * @param  Validator  $validator
+     * @param  AccountValidator  $accountValidator
+     * @param  array  $transaction
+     * @param  string  $transactionType
+     * @param  int  $index
+     * @return void
+     */
+    private function sanityCheckForeignCurrency(
+        Validator $validator,
+        AccountValidator $accountValidator,
+        array $transaction,
+        string $transactionType,
+        int $index
+    ): void {
+        Log::debug('Now in sanityCheckForeignCurrency()');
+        if (0 !== $validator->errors()->count()) {
+            Log::debug('Already have errors, return');
+            return;
+        }
+        if (null === $accountValidator->source) {
+            Log::debug('No source, return');
+            return;
+        }
+        if (null === $accountValidator->destination) {
+            Log::debug('No destination, return');
+            return;
+        }
+        $source      = $accountValidator->source;
+        $destination = $accountValidator->destination;
+
+        Log::debug(sprintf('Source: #%d "%s (%s)"', $source->id, $source->name, $source->accountType->type));
+        Log::debug(sprintf('Destination: #%d "%s" (%s)', $destination->id, $destination->name, $source->accountType->type));
+
+        if (!$this->isLiabilityOrAsset($source) || !$this->isLiabilityOrAsset($destination)) {
+            Log::debug('Any account must be liability or asset account to continue.');
+            return;
         }
 
-        // withdrawal or transfer and the destination is a liability or an asset account with a different
-        // currency than submitted? then the foreign currency info must be present as well (and filled in).
-        if (0 === $validator->errors()->count() && null !== $accountValidator->destination &&
-            (TransactionType::WITHDRAWAL === ucfirst($transactionType) || (TransactionType::TRANSFER === ucfirst($transactionType)))) {
-            $accountType = $accountValidator?->destination?->accountType?->type;
-            if (in_array($accountType, config('firefly.valid_currency_account_types'), true) && !$this->hasForeignCurrencyInfo($transaction)) {
+
+        /** @var AccountRepositoryInterface $accountRepository */
+        $accountRepository   = app(AccountRepositoryInterface::class);
+        $defaultCurrency     = app('amount')->getDefaultCurrency();
+        $sourceCurrency      = $accountRepository->getAccountCurrency($source) ?? $defaultCurrency;
+        $destinationCurrency = $accountRepository->getAccountCurrency($destination) ?? $defaultCurrency;
+        // if both accounts have the same currency, continue.
+        if ($sourceCurrency->code === $destinationCurrency->code) {
+            Log::debug('Both accounts have the same currency, continue.');
+            return;
+        }
+
+        if (TransactionType::DEPOSIT === ucfirst($transactionType)) {
+            // use case: deposit from liability account to an asset account
+            // the foreign amount must be in the currency of the source
+            // the amount must be in the currency of the destination
+
+            // no foreign currency information is present:
+            if (!$this->hasForeignCurrencyInfo($transaction)) {
                 $validator->errors()->add(sprintf('transactions.%d.foreign_amount', $index), (string)trans('validation.require_foreign_currency'));
+                return;
+            }
+
+            // wrong currency information is present
+            $foreignCurrencyCode = $transaction['foreign_currency_code'] ?? false;
+            if ($foreignCurrencyCode !== $sourceCurrency->code) {
+                $validator->errors()->add(sprintf('transactions.%d.foreign_currency_code', $index), (string)trans('validation.require_foreign_src'));
+                return;
             }
         }
-        // account validator has a valid source and a valid destination
+        if (TransactionType::TRANSFER === ucfirst($transactionType) || TransactionType::WITHDRAWAL === ucfirst($transactionType)) {
+            // use case: withdrawal from asset account to a liability account.
+            // the foreign amount must be in the currency of the destination
+            // the amount must be in the currency of the source
+
+            // use case: transfer between accounts with different currencies.
+            // the foreign amount must be in the currency of the destination
+            // the amount must be in the currency of the source
+
+            // no foreign currency information is present:
+            if (!$this->hasForeignCurrencyInfo($transaction)) {
+                $validator->errors()->add(sprintf('transactions.%d.foreign_amount', $index), (string)trans('validation.require_foreign_currency'));
+                return;
+            }
+
+            // wrong currency information is present
+            $foreignCurrencyCode = $transaction['foreign_currency_code'] ?? false;
+            if ($foreignCurrencyCode !== $destinationCurrency->code) {
+                $validator->errors()->add(sprintf('transactions.%d.foreign_currency_code', $index), (string)trans('validation.require_foreign_dest'));
+            }
+        }
+    }
+
+    /**
+     * @param  Account  $account
+     * @return bool
+     */
+    private function isLiabilityOrAsset(Account $account): bool
+    {
+        return $this->isLiability($account) || $this->isAsset($account);
+    }
+
+    /**
+     * @param  Account  $account
+     * @return bool
+     */
+    private function isLiability(Account $account): bool
+    {
+        $type = $account->accountType?->type;
+        if (in_array($type, config('firefly.valid_liabilities'), true)) {
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * @param  Account  $account
+     * @return bool
+     */
+    private function isAsset(Account $account): bool
+    {
+        $type = $account->accountType?->type;
+        return $type === AccountType::ASSET;
     }
 
     /**
diff --git a/resources/lang/en_US/validation.php b/resources/lang/en_US/validation.php
index 924831adc8..d90ab1969b 100644
--- a/resources/lang/en_US/validation.php
+++ b/resources/lang/en_US/validation.php
@@ -57,6 +57,8 @@ return [
     'not_transfer_account'           => 'This account is not an account that can be used for transfers.',
     'require_currency_amount'        => 'The content of this field is invalid without foreign amount information.',
     'require_foreign_currency'       => 'This field requires a number',
+    'require_foreign_dest'           => 'This field value must match the currency of the destination account.',
+    'require_foreign_src'            => 'This field value must match the currency of the source account.',
     'equal_description'              => 'Transaction description should not equal global description.',
     'file_invalid_mime'              => 'File ":name" is of type ":mime" which is not accepted as a new upload.',
     'file_too_large'                 => 'File ":name" is too large.',