Add ability to define Payer as a WHM Employer

src/Entities/Payer.php

@@ -6,4 +6,13 @@
 
 interface Payer
 {
+    /**
+     * Determines if the payer is a registered Working Holiday Maker employer.
+     *
+     * In order to withhold tax for employees at a Working Holiday Maker rate, the payer must be registered as a
+     * Working Holiday Maker employer with the ATO. Otherwise, the employees are classified as foreign workers.
+     *
+     * @return bool
+     */
+    public function isRegisteredWhmEmployer(): bool;
 }

src/TaxScales/October2020/Nat1004Scale3.php

@@ -36,8 +36,11 @@ public function isEligible(Payer $payer, Payee $payee, Earning $earning): bool
             return false;
         }
 
-        // Only applies to foreign residents.
-        if ($payee->getResidencyStatus() !== \ManageIt\PaygTax\Entities\Payee::FOREIGN_RESIDENT) {
+        // Only applies to foreign residents (or Working Holiday Makers whose employers are not registered)
+        if (
+            $payee->getResidencyStatus() === \ManageIt\PaygTax\Entities\Payee::RESIDENT
+            || ($payee->getResidencyStatus() === \ManageIt\PaygTax\Entities\Payee::WORKING_HOLIDAY_MAKER && $payer->isRegisteredWhmEmployer())
+        ) {
             return false;
         }
 

src/TaxScales/October2020/Nat1004Scale4.php

@@ -34,8 +34,8 @@ public function isEligible(Payer $payer, Payee $payee, Earning $earning): bool
             return false;
         }
 
-        // Working Holiday Makers still use their own tax scale.
-        if ($payee->getResidencyStatus() === Payee::WORKING_HOLIDAY_MAKER) {
+        // Working Holiday Makers still use their own tax scale if their payer is registered as a WHM employer.
+        if ($payee->getResidencyStatus() === Payee::WORKING_HOLIDAY_MAKER  && $payer->isRegisteredWhmEmployer()) {
             return false;
         }
 

src/TaxScales/October2020/Nat75331.php

@@ -36,6 +36,11 @@ public function isEligible(Payer $payer, Payee $payee, Earning $earning): bool
             return false;
         }
 
+        // Only applies if the payer is registered as a Working Holiday Maker employer.
+        if (!$payer->isRegisteredWhmEmployer()) {
+            return false;
+        }
+
         return true;
     }
 

tests/Fixtures/Payer.php

@@ -6,4 +6,10 @@
 
 class Payer implements PayerInterface
 {
+    public bool $whmEmployer = true;
+
+    public function isRegisteredWhmEmployer(): bool
+    {
+        return $this->whmEmployer;
+    }
 }

tests/TaxScales/October2020/Nat1004Scale3Test.php

@@ -46,6 +46,10 @@ public function testEligibility(): void
         $payee->residencyStatus = Payee::WORKING_HOLIDAY_MAKER;
         Assert::assertFalse($this->scale->isEligible($payer, $payee, $earning));
 
+        $payer->whmEmployer = false;
+        Assert::assertTrue($this->scale->isEligible($payer, $payee, $earning));
+
+        $payer->whmEmployer = true;
         $payee->residencyStatus = Payee::FOREIGN_RESIDENT;
         $payee->tfn = false;
         Assert::assertFalse($this->scale->isEligible($payer, $payee, $earning));

tests/TaxScales/October2020/Nat1004Scale4Test.php

@@ -43,6 +43,10 @@ public function testEligibility(): void
         $payee->residencyStatus = Payee::WORKING_HOLIDAY_MAKER;
         Assert::assertFalse($this->scale->isEligible($payer, $payee, $earning));
 
+        $payer->whmEmployer = false;
+        Assert::assertTrue($this->scale->isEligible($payer, $payee, $earning));
+
+        $payer->whmEmployer = true;
         $payee->residencyStatus = Payee::RESIDENT;
         $payee->tfn = true;
         Assert::assertFalse($this->scale->isEligible($payer, $payee, $earning));