diff --git a/src/app/Http/Controllers/API/V4/PaymentsController.php b/src/app/Http/Controllers/API/V4/PaymentsController.php
--- a/src/app/Http/Controllers/API/V4/PaymentsController.php
+++ b/src/app/Http/Controllers/API/V4/PaymentsController.php
@@ -198,16 +198,9 @@
         // Validate the minimum value
         // It has to be at least minimum payment amount and must cover current debt,
         // and must be more than a yearly/monthly payment (according to the plan)
-        $min = Payment::MIN_AMOUNT;
+        $min = $wallet->getMinMandateAmount();
         $label = 'minamount';
 
-        if (($plan = $wallet->plan()) && $plan->months >= 1) {
-            $planCost = $plan->cost() * $plan->months;
-            if ($planCost > $min) {
-                $min = $planCost;
-            }
-        }
-
         if ($wallet->balance < 0 && $wallet->balance < $min * -1) {
             $min = $wallet->balance * -1;
             $label = 'minamountdebt';
@@ -436,7 +429,7 @@
         // Get the Mandate info
         $mandate = (array) $provider->getMandate($wallet);
 
-        $mandate['amount'] = $mandate['minAmount'] = (int) ceil(Payment::MIN_AMOUNT / 100);
+        $mandate['amount'] = $mandate['minAmount'] = round($wallet->getMinMandateAmount() / 100, 2);
         $mandate['balance'] = 0;
         $mandate['isDisabled'] = !empty($mandate['id']) && $settings['mandate_disabled'];
         $mandate['isValid'] = !empty($mandate['isValid']);
@@ -447,14 +440,6 @@
             }
         }
 
-        // If this is a multi-month plan, we calculate the expected amount to be payed.
-        if (($plan = $wallet->plan()) && $plan->months >= 1) {
-            $planCost = round($plan->cost() * $plan->months / 100, 2);
-            if ($planCost > $mandate['minAmount']) {
-                $mandate['minAmount'] = $planCost;
-            }
-        }
-
         // Unrestrict the wallet owner if mandate is valid
         if (!empty($mandate['isValid']) && $wallet->owner->isRestricted()) {
             $wallet->owner->unrestrict();
diff --git a/src/app/Wallet.php b/src/app/Wallet.php
--- a/src/app/Wallet.php
+++ b/src/app/Wallet.php
@@ -420,11 +420,9 @@
     /**
      * Return the exact, numeric version of the discount to be applied.
      *
-     * Ranges from 0 - 100.
-     *
-     * @return int
+     * @return int Discount in percent, ranges from 0 - 100.
      */
-    public function getDiscount()
+    public function getDiscount(): int
     {
         return $this->discount ? $this->discount->discount : 0;
     }
@@ -432,14 +430,34 @@
     /**
      * The actual discount rate for use in multiplication
      *
-     * Ranges from 0.00 to 1.00.
+     * @return float Discount rate, ranges from 0.00 to 1.00.
      */
-    public function getDiscountRate()
+    public function getDiscountRate(): float
     {
         return (100 - $this->getDiscount()) / 100;
     }
 
     /**
+     * The minimum amount of an auto-payment mandate
+     *
+     * @return int Amount in cents
+     */
+    public function getMinMandateAmount(): int
+    {
+        $min = Payment::MIN_AMOUNT;
+
+        if ($plan = $this->plan()) {
+            $planCost = (int) ($plan->cost() * $plan->months * $this->getDiscountRate());
+
+            if ($planCost > $min) {
+                $min = $planCost;
+            }
+        }
+
+        return $min;
+    }
+
+    /**
      * Check if the specified user is a controller to this wallet.
      *
      * @param \App\User $user The user object.
diff --git a/src/tests/Feature/WalletTest.php b/src/tests/Feature/WalletTest.php
--- a/src/tests/Feature/WalletTest.php
+++ b/src/tests/Feature/WalletTest.php
@@ -2,6 +2,7 @@
 
 namespace Tests\Feature;
 
+use App\Discount;
 use App\Payment;
 use App\Package;
 use App\Plan;
@@ -59,6 +60,7 @@
         Sku::select()->update(['fee' => 0]);
         Payment::query()->delete();
         VatRate::query()->delete();
+        Plan::withEnvTenantContext()->where('title', 'individual')->update(['months' => 1]);
 
         parent::tearDown();
     }
@@ -279,7 +281,7 @@
     /**
      * Verify a wallet can be assigned a controller.
      */
-    public function testAddWalletController(): void
+    public function testAddController(): void
     {
         $userA = $this->getTestUser('WalletControllerA@WalletController.com');
         $userB = $this->getTestUser('WalletControllerB@WalletController.com');
@@ -299,6 +301,35 @@
     }
 
     /**
+     * Test Wallet::getMinMandateAmount()
+     */
+    public function testGetMinMandateAmount(): void
+    {
+        $user = $this->getTestUser('WalletControllerA@WalletController.com');
+        $user->setSetting('plan_id', null);
+        $wallet = $user->wallets()->first();
+
+        // No plan assigned
+        $this->assertSame(Payment::MIN_AMOUNT, $wallet->getMinMandateAmount());
+
+        // Plan assigned
+        $plan = Plan::withEnvTenantContext()->where('title', 'individual')->first();
+        $plan->months = 12;
+        $plan->save();
+
+        $user->setSetting('plan_id', $plan->id);
+
+        $this->assertSame(990 * 12, $wallet->getMinMandateAmount());
+
+        // Plan and discount
+        $discount = Discount::where('discount', 30)->first();
+        $wallet->discount()->associate($discount);
+        $wallet->save();
+
+        $this->assertSame((int) (990 * 12 * 0.70), $wallet->getMinMandateAmount());
+    }
+
+    /**
      * Test Wallet::isController()
      */
     public function testIsController(): void