diff --git a/app/Http/Requests/Payment/StorePaymentRequest.php b/app/Http/Requests/Payment/StorePaymentRequest.php
index 1bb5808b82e8..000a07d6ac01 100644
--- a/app/Http/Requests/Payment/StorePaymentRequest.php
+++ b/app/Http/Requests/Payment/StorePaymentRequest.php
@@ -78,7 +78,6 @@ class StorePaymentRequest extends Request
             foreach ($input['credits'] as $key => $value) {
                 if (array_key_exists('credit_id', $input['credits'][$key])) {
                     $input['credits'][$key]['credit_id'] = $this->decodePrimaryKey($value['credit_id']);
-
                     $credits_total += $value['amount'];
                 }
             }
diff --git a/app/Http/Requests/Payment/UpdatePaymentRequest.php b/app/Http/Requests/Payment/UpdatePaymentRequest.php
index f4b90758adcf..d24ed6b32d89 100644
--- a/app/Http/Requests/Payment/UpdatePaymentRequest.php
+++ b/app/Http/Requests/Payment/UpdatePaymentRequest.php
@@ -44,7 +44,8 @@ class UpdatePaymentRequest extends Request
 
         $rules = [
             'invoices' => ['array', new PaymentAppliedValidAmount($this->all()), new ValidCreditsPresentRule($this->all())],
-            'invoices.*.invoice_id' => 'distinct',
+            'invoices.*.invoice_id' => 'sometimes|distinct',
+            'invoices.*.amount' => 'sometimes|numeric|min:0',
         ];
 
         if ($this->number) {
@@ -85,7 +86,6 @@ class UpdatePaymentRequest extends Request
         if (isset($input['invoices']) && is_array($input['invoices']) !== false) {
             foreach ($input['invoices'] as $key => $value) {
                 if(isset($input['invoices'][$key]['invoice_id'])) {
-                    // if (array_key_exists('invoice_id', $input['invoices'][$key])) {
                     $input['invoices'][$key]['invoice_id'] = $this->decodePrimaryKey($value['invoice_id']);
                 }
             }
@@ -93,7 +93,6 @@ class UpdatePaymentRequest extends Request
 
         if (isset($input['credits']) && is_array($input['credits']) !== false) {
             foreach ($input['credits'] as $key => $value) {
-                // if (array_key_exists('credits', $input['credits'][$key])) {
                 if (isset($input['credits'][$key]['credit_id'])) {
                     $input['credits'][$key]['credit_id'] = $this->decodePrimaryKey($value['credit_id']);
                 }
diff --git a/app/Http/ValidationRules/PaymentAppliedValidAmount.php b/app/Http/ValidationRules/PaymentAppliedValidAmount.php
index 06f83315b288..863b56d68986 100644
--- a/app/Http/ValidationRules/PaymentAppliedValidAmount.php
+++ b/app/Http/ValidationRules/PaymentAppliedValidAmount.php
@@ -87,10 +87,6 @@ class PaymentAppliedValidAmount implements Rule
 
                 $inv = $inv_collection->firstWhere('id', $invoice['invoice_id']);
 
-                nlog($inv->status_id);
-                nlog($inv->amount);
-                nlog($invoice['amount']);
-
                 if($inv->status_id == Invoice::STATUS_DRAFT && $inv->amount >= $invoice['amount']) {
 
                 } elseif ($inv->balance < $invoice['amount']) {
diff --git a/app/Http/ValidationRules/ValidCreditsPresentRule.php b/app/Http/ValidationRules/ValidCreditsPresentRule.php
index 7dfb07df5f99..877a0c1d3e1d 100644
--- a/app/Http/ValidationRules/ValidCreditsPresentRule.php
+++ b/app/Http/ValidationRules/ValidCreditsPresentRule.php
@@ -49,11 +49,8 @@ class ValidCreditsPresentRule implements Rule
 
     private function validCreditsPresent(): bool
     {
-        //todo need to ensure the clients credits are here not random ones!
-
         if (array_key_exists('credits', $this->input) && is_array($this->input['credits']) && count($this->input['credits']) > 0) {
-            $credit_collection = Credit::query()->whereIn('id', array_column($this->input['credits'], 'credit_id'))->count();
-
+            $credit_collection = Credit::query()->where('client_id', request()->input('client_id'))->whereIn('id', array_column($this->input['credits'], 'credit_id'))->count();
             return $credit_collection == count($this->input['credits']);
         }
 
diff --git a/tests/Feature/PaymentTest.php b/tests/Feature/PaymentTest.php
index cba90ac705d5..dcadebe4f301 100644
--- a/tests/Feature/PaymentTest.php
+++ b/tests/Feature/PaymentTest.php
@@ -62,6 +62,74 @@ class PaymentTest extends TestCase
         );
     }
 
+    public function testNegativeAppliedAmounts()
+    {
+        $p = Payment::factory()->create([
+            'company_id' => $this->company->id,
+            'user_id' => $this->user->id,
+            'client_id' => $this->client->id,
+            'status_id' => Payment::STATUS_COMPLETED,
+            'amount' => 100
+        ]);
+
+        $i = Invoice::factory()->create([
+            'company_id' => $this->company->id,
+            'user_id' => $this->user->id,
+            'client_id' => $this->client->id,
+            'status_id' => Invoice::STATUS_SENT,
+        ]);
+
+        $i->calc()->getInvoice()->service()->markSent()->save();
+
+        $this->assertGreaterThan(0, $i->balance);
+        
+
+        $data = [
+            'amount' => 5,
+            'client_id' => $this->client->hashed_id,
+            'invoices' => [
+                [
+                    'invoice_id' => $this->invoice->hashed_id,
+                    'amount' => 5,
+                ],
+            ],
+            'date' => '2020/12/11',
+            'idempotency_key' => \Illuminate\Support\Str::uuid()->toString()
+        ];
+
+        $response = $this->withHeaders([
+            'X-API-SECRET' => config('ninja.api_secret'),
+            'X-API-TOKEN' => $this->token,
+        ])->postJson('/api/v1/payments/', $data);
+
+        $response->assertStatus(200);
+
+        $payment_id = $response->json()['data']['id'];
+
+        $payment = Payment::find($this->decodePrimaryKey($payment_id));
+        
+        $this->assertNotNull($payment);
+
+        $data = [
+            'client_id' => $this->client->hashed_id,
+            'invoices' => [
+                [
+                    'invoice_id' => $this->invoice->hashed_id,
+                    'amount' => -5,
+                ],
+            ],
+            'date' => '2020/12/11',
+            'idempotency_key' => \Illuminate\Support\Str::uuid()->toString()
+        ];
+
+        $response = $this->withHeaders([
+            'X-API-SECRET' => config('ninja.api_secret'),
+            'X-API-TOKEN' => $this->token,
+        ])->putJson('/api/v1/payments/'.$payment_id, $data);
+
+        $response->assertStatus(422);
+
+    }
 
     public function testCompletedPaymentLogic()
     {
@@ -1395,8 +1463,9 @@ class PaymentTest extends TestCase
         $invoice_calc = new InvoiceSum($invoice);
         $invoice_calc->build();
 
-        $invoice = $invoice_calc->getInvoice();
-        $invoice->save();
+        $invoice = $invoice_calc->getInvoice()->service()->markSent()->save();
+        $this->assertEquals(10, $invoice->amount);
+        $this->assertEquals(10, $invoice->balance);
 
         $credit = CreditFactory::create($this->company->id, $this->user->id);
         $credit->client_id = $client->id;
@@ -1410,8 +1479,10 @@ class PaymentTest extends TestCase
         $credit_calc = new InvoiceSum($credit);
         $credit_calc->build();
 
-        $credit = $credit_calc->getCredit();
-        $credit->save(); //$10 credit
+        $credit = $credit_calc->getCredit()->service()->markSent()->save(); //$10 credit
+
+        $this->assertEquals(10, $credit->amount);
+        $this->assertEquals(10, $credit->balance);
 
         $data = [
             'amount' => $invoice->amount,
diff --git a/tests/Feature/Payments/CreditPaymentTest.php b/tests/Feature/Payments/CreditPaymentTest.php
index 465a3d7f0cc6..1ecde31a3018 100644
--- a/tests/Feature/Payments/CreditPaymentTest.php
+++ b/tests/Feature/Payments/CreditPaymentTest.php
@@ -163,18 +163,11 @@ class CreditPaymentTest extends TestCase
             'date' => '2019/12/12',
         ];
 
-        $response = false;
-
-        try {
-            $response = $this->withHeaders([
-                'X-API-SECRET' => config('ninja.api_secret'),
-                'X-API-TOKEN' => $this->token,
-            ])->post('/api/v1/payments/', $data);
-        } catch (ValidationException $e) {
-            $message = json_decode($e->validator->getMessageBag(), 1);
-            nlog($e->validator->getMessageBag());
-        }
-
+        $response = $this->withHeaders([
+            'X-API-SECRET' => config('ninja.api_secret'),
+            'X-API-TOKEN' => $this->token,
+        ])->postJson('/api/v1/payments/', $data);
+    
         $response->assertStatus(200);
 
         $arr = $response->json();
diff --git a/tests/Feature/RefundTest.php b/tests/Feature/RefundTest.php
index 002a3eb43256..e27c89c80dfb 100644
--- a/tests/Feature/RefundTest.php
+++ b/tests/Feature/RefundTest.php
@@ -63,127 +63,126 @@ class RefundTest extends TestCase
     public function testRefundAndAppliedAmounts()
     {
 
+        $data = [
+            'amount' => 500,
+            'client_id' => $this->client->hashed_id,
+            'date' => '2020/12/12',
 
-$data = [
-    'amount' => 500,
-    'client_id' => $this->client->hashed_id,
-    'date' => '2020/12/12',
+        ];
 
-];
+        $response = $this->withHeaders([
+            'X-API-SECRET' => config('ninja.api_secret'),
+            'X-API-TOKEN' => $this->token,
+        ])->postJson('/api/v1/payments', $data);
 
-$response = $this->withHeaders([
-    'X-API-SECRET' => config('ninja.api_secret'),
-    'X-API-TOKEN' => $this->token,
-])->postJson('/api/v1/payments', $data);
+        $response->assertStatus(200);
 
-$response->assertStatus(200);
+        $arr = $response->json();
 
-$arr = $response->json();
+        $payment_id = $arr['data']['id'];
 
-$payment_id = $arr['data']['id'];
+        $item = new InvoiceItem;
+        $item->cost = 300;
+        $item->quantity = 1;
 
-$item = new InvoiceItem;
-$item->cost = 300;
-$item->quantity = 1;
+        $i = Invoice::factory()
+        ->create([
+            'user_id' => $this->user->id,
+            'company_id' => $this->company->id,
+            'client_id' => $this->client->id,
+            'line_items' => [$item],
+            'discount' => 0,
+            'tax_name1' => '',
+            'tax_name2' => '',
+            'tax_name3' => '',
+            'tax_rate1' => 0,
+            'tax_rate2' => 0,
+            'tax_rate3' => 0,
+        ]);
 
-$i = Invoice::factory()
-->create([
-    'user_id' => $this->user->id,
-    'company_id' => $this->company->id,
-    'client_id' => $this->client->id,
-    'line_items' => [$item],
-    'discount' => 0,
-    'tax_name1' => '',
-    'tax_name2' => '',
-    'tax_name3' => '',
-    'tax_rate1' => 0,
-    'tax_rate2' => 0,
-    'tax_rate3' => 0,
-]);
+        $i->calc()->getInvoice();
+        $i->service()->markSent()->save();
 
-$i->calc()->getInvoice();
-$i->service()->markSent()->save();
+        $this->assertEquals(300, $i->balance);
 
-$this->assertEquals(300, $i->balance);
+        $data = [
+            'client_id' => $this->client->hashed_id,
+            'invoices' => [
+                [
+                'invoice_id' => $i->hashed_id,
+                'amount' => 300
+                ],
+            ]
+        ];
 
-$data = [
-    'client_id' => $this->client->hashed_id,
-    'invoices' => [
-        [
-        'invoice_id' => $i->hashed_id,
-        'amount' => 300
-        ],
-    ]
-];
+        $response = $this->withHeaders([
+            'X-API-SECRET' => config('ninja.api_secret'),
+            'X-API-TOKEN' => $this->token,
+        ])->putJson('/api/v1/payments/'.$payment_id, $data);
 
-$response = $this->withHeaders([
-    'X-API-SECRET' => config('ninja.api_secret'),
-    'X-API-TOKEN' => $this->token,
-])->putJson('/api/v1/payments/'.$payment_id, $data);
+        $response->assertStatus(200);
 
-$response->assertStatus(200);
+        $i = $i->fresh();
 
-$i = $i->fresh();
+        $this->assertEquals(0, $i->balance);
 
-$this->assertEquals(0, $i->balance);
+        $payment = Payment::find($this->decodePrimaryKey($payment_id));
 
-$payment = Payment::find($this->decodePrimaryKey($payment_id));
+        $this->assertNotNull($payment);
+        $this->assertEquals(500, $payment->amount);
+        $this->assertEquals(300, $payment->applied);
+        $this->assertEquals(0, $payment->refunded);
 
-$this->assertNotNull($payment);
-$this->assertEquals(500, $payment->amount);
-$this->assertEquals(300, $payment->applied);
-$this->assertEquals(0, $payment->refunded);
+        $data = [
+            'id' => $this->encodePrimaryKey($payment->id),
+            'invoices' => [
+                [
+                    'invoice_id' => $i->hashed_id,
+                    'amount' => $i->amount,
+                ],
+            ],
+            'date' => '2020/12/12',
+        ];
 
-$data = [
-    'id' => $this->encodePrimaryKey($payment->id),
-    'invoices' => [
-        [
-            'invoice_id' => $i->hashed_id,
-            'amount' => $i->amount,
-        ],
-    ],
-    'date' => '2020/12/12',
-];
+        $response = $this->withHeaders([
+            'X-API-SECRET' => config('ninja.api_secret'),
+            'X-API-TOKEN' => $this->token,
+        ])->postJson('/api/v1/payments/refund', $data);
 
-$response = $this->withHeaders([
-    'X-API-SECRET' => config('ninja.api_secret'),
-    'X-API-TOKEN' => $this->token,
-])->postJson('/api/v1/payments/refund', $data);
+        $response->assertStatus(200);
 
-$response->assertStatus(200);
+        $payment = $payment->fresh();
+        $i = $i->fresh();
 
-$payment = $payment->fresh();
-$i = $i->fresh();
-
-$this->assertEquals(300, $payment->refunded);
-$this->assertEquals(300, $i->balance);
-$this->assertEquals(2, $i->status_id);
+        $this->assertEquals(300, $payment->refunded);
+        $this->assertEquals(300, $i->balance);
+        $this->assertEquals(2, $i->status_id);
 
 
-$data = [
-    'client_id' => $this->client->hashed_id,
-    'invoices' => [
-        [
-        'invoice_id' => $i->hashed_id,
-        'amount' => 200
-        ],
-    ]
-];
+        $data = [
+            'client_id' => $this->client->hashed_id,
+            'invoices' => [
+                [
+                'invoice_id' => $i->hashed_id,
+                'amount' => 200
+                ],
+            ]
+        ];
 
-$response = $this->withHeaders([
-    'X-API-SECRET' => config('ninja.api_secret'),
-    'X-API-TOKEN' => $this->token,
-])->putJson('/api/v1/payments/'.$payment_id, $data);
+        $response = $this->withHeaders([
+            'X-API-SECRET' => config('ninja.api_secret'),
+            'X-API-TOKEN' => $this->token,
+        ])->putJson('/api/v1/payments/'.$payment_id, $data);
 
-$response->assertStatus(200);
+        $response->assertStatus(200);
 
-$payment = $payment->fresh();
-$i = $i->fresh();
+        $payment = $payment->fresh();
+        $i = $i->fresh();
 
-$this->assertEquals(300, $payment->refunded);
-$this->assertEquals(100, $i->balance);
-$this->assertEquals(3, $i->status_id);
-$this->assertEquals(500, $payment->applied);
+        $this->assertEquals(300, $payment->refunded);
+        $this->assertEquals(100, $i->balance);
+        $this->assertEquals(3, $i->status_id);
+        $this->assertEquals(500, $payment->applied);
 
     }