diff --git a/app/Helpers/Invoice/Refund.php b/app/Helpers/Invoice/ProRata.php
similarity index 55%
rename from app/Helpers/Invoice/Refund.php
rename to app/Helpers/Invoice/ProRata.php
index e4e12dd0b9..4026d41d30 100644
--- a/app/Helpers/Invoice/Refund.php
+++ b/app/Helpers/Invoice/ProRata.php
@@ -11,13 +11,24 @@
 
 namespace App\Helpers\Invoice;
 
+use App\Models\Invoice;
 use App\Models\RecurringInvoice;
+use Carbon\Exceptions\InvalidFormatException;
+use Exception;
+use Illuminate\Contracts\Container\BindingResolutionException;
 use Illuminate\Support\Carbon;
 
-class Refund
+class ProRata
 {
 
-    public function proRata(float $amount, Carbon $from_date, Carbon $to_date, int $frequency) :float
+    /**
+     * @param float $amount 
+     * @param Carbon $from_date 
+     * @param Carbon $to_date 
+     * @param int $frequency 
+     * @return float 
+     */
+    public function refund(float $amount, Carbon $from_date, Carbon $to_date, int $frequency) :float
     {
         $days = $from_date->diffInDays($to_date);
         $days_in_frequency = $this->getDaysInFrequency($frequency);
@@ -25,6 +36,53 @@ class Refund
         return round( (($days/$days_in_frequency) * $amount),2);
     }
 
+
+    /**
+     * Prepares the line items of an invoice
+     * to be pro rata refunded.
+     * 
+     * @param Invoice $invoice 
+     * @param bool $is_credit 
+     * @return array 
+     * @throws Exception 
+     */
+    public function refundItems(Invoice $invoice, $is_credit = false) :array
+    {
+        if(!$invoice)
+            return [];
+
+        $recurring_invoice = RecurringInvoice::find($invoice->recurring_id)->first();
+
+        if(!$recurring_invoice)
+            throw new \Exception("Invoice isn't attached to a recurring invoice");
+
+        /* depending on whether we are creating an invoice or a credit*/
+        $multiplier = $is_credit ? 1 : -1;
+
+        $start_date = Carbon::parse($invoice->date);
+
+        $line_items = [];
+
+        foreach($invoice->line_items as $item)
+        {
+
+            if($item->product_key != ctrans('texts.refund'))
+            {
+                $item->quantity = 1;
+                $item->cost = $this->refund($item->cost*$multiplier, $start_date, now(), $recurring_invoice->frequency_id);
+                $item->product_key = ctrans('texts.refund');
+                $item->notes = ctrans('texts.refund') . ": ". $item->notes;
+
+                $line_items[] = $item;
+
+            }
+        }
+
+        return $line_items;
+
+    }
+
+
     private function getDaysInFrequency($frequency)
     {
 
diff --git a/app/Helpers/Subscription/SubscriptionCalculator.php b/app/Helpers/Subscription/SubscriptionCalculator.php
new file mode 100644
index 0000000000..597f727ca6
--- /dev/null
+++ b/app/Helpers/Subscription/SubscriptionCalculator.php
@@ -0,0 +1,48 @@
+<?php
+/**
+ * Invoice Ninja (https://invoiceninja.com).
+ *
+ * @link https://github.com/invoiceninja/invoiceninja source repository
+ *
+ * @copyright Copyright (c) 2021. Invoice Ninja LLC (https://invoiceninja.com)
+ *
+ * @license https://www.elastic.co/licensing/elastic-license
+ */
+
+namespace App\Helpers\Subscription;
+
+use App\Models\Invoice;
+use App\Models\RecurringInvoice;
+use App\Models\Subscription;
+
+/**
+ * SubscriptionCalculator.
+ */
+class SubscriptionCalculator 
+{
+    public Subscription $subscription;
+
+    public function __construct(Subscription $subscription)
+    {
+        $this->subscription = $subscription;
+    }
+
+    /**
+     * Tests if the user is currently up
+     * to date with their payments for
+     * a given recurring invoice
+     *     
+     * @return bool
+     */
+    public function isPaidUp(RecurringInvoice $recurring_invoice) :bool
+    {
+
+        $outstanding_invoices_exist = Invoice::whereIn('status_id', [Invoice::STATUS_SENT, Invoice::STATUS_PARTIAL])
+                                               ->where('recurring_id', $recurring_invoice->id)
+                                               ->where('balance', '>', 0)
+                                               ->exists();
+
+       return ! $outstanding_invoices_exist;
+
+    }
+}
\ No newline at end of file
diff --git a/tests/Unit/RefundUnitTest.php b/tests/Unit/RefundUnitTest.php
index bfecc4b616..fe930e0a0c 100644
--- a/tests/Unit/RefundUnitTest.php
+++ b/tests/Unit/RefundUnitTest.php
@@ -10,7 +10,7 @@
  */
 namespace Tests\Unit;
 
-use App\Helpers\Invoice\Refund;
+use App\Helpers\Invoice\ProRata;
 use App\Models\RecurringInvoice;
 use App\Utils\Ninja;
 use Illuminate\Support\Carbon;
@@ -29,8 +29,8 @@ class RefundUnitTest extends TestCase
 
     public function testProRataRefundMonthly()
     {
-        $r = new Refund();
-        $refund = $r->proRata(10, Carbon::parse('2021-01-01'), Carbon::parse('2021-01-31'), RecurringInvoice::FREQUENCY_MONTHLY);
+        $pro_rata = new ProRata();
+        $refund = $pro_rata->refund(10, Carbon::parse('2021-01-01'), Carbon::parse('2021-01-31'), RecurringInvoice::FREQUENCY_MONTHLY);
 
         $this->assertEquals(9.68, $refund);
 
@@ -40,9 +40,9 @@ class RefundUnitTest extends TestCase
 
     public function testProRataRefundYearly()
     {
-        $r = new Refund();
+        $pro_rata = new ProRata();
 
-        $refund = $r->proRata(10, Carbon::parse('2021-01-01'), Carbon::parse('2021-01-31'), RecurringInvoice::FREQUENCY_ANNUALLY);
+        $refund = $pro_rata->refund(10, Carbon::parse('2021-01-01'), Carbon::parse('2021-01-31'), RecurringInvoice::FREQUENCY_ANNUALLY);
 
         $this->assertEquals(0.82, $refund);
     }