Implement 2024/25 tax tables, simplify library usage (#1)

README.md

@@ -22,11 +22,11 @@ composer require manageitwa/payg-tax
 
 This library is built to be able to be slotted in to most PHP software. The library publishes a number of interfaces within the `src/Entities` directory. At a bare minimum, you would need to fulfill the following interfaces:
 
-- `Payer`: A payer record. The payer is generally the employer or the entity who is paying the payee.
+- `Payer`: A payer record. The payer is the employer or the entity who is paying the payee.
 - `Payee`: A payee record. The payee is the employee or entity who is being paid the gross income and needs income tax to be withheld from their earning.
 - `Earning`: An earning record. The earning is a single gross amount of income that is paid either ad-hoc or as part of a pay cycle to the payee.
 
-In general, you would like implement these interfaces into a model record for each of these entities.
+In general, you would likely implement these interfaces into a model record for each of these entities.
 
 ```php
 <?php

src/Adjustments/July2024/MedicareLevyReduction.php

@@ -0,0 +1,135 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ManageIt\PaygTax\Adjustments\July2024;
+
+use ManageIt\PaygTax\Entities\Payer;
+use ManageIt\PaygTax\Entities\Payee;
+use ManageIt\PaygTax\Entities\Earning;
+use ManageIt\PaygTax\Entities\TaxScale;
+use ManageIt\PaygTax\Traits\WeeklyConversion;
+use ManageIt\PaygTax\Utilities\Math;
+
+class MedicareLevyReduction
+{
+    use WeeklyConversion;
+
+    /**
+     * Whether the payee is claiming to have a spouse.
+     */
+    public bool $spouse = true;
+
+    /**
+     * The number of children the payee is claiming for the Medicare Levy Reduction.
+     */
+    public int $children = 0;
+
+    public function __construct(bool $spouse = true, int $children = 0)
+    {
+        $this->spouse = $spouse;
+        $this->children = $children;
+    }
+
+    public function getAdjustmentAmount(Payer $payer, Payee $payee, TaxScale $taxScale, Earning $earning): float
+    {
+        $weeklyGross = $this->getWeeklyGross(
+            $payee->getPayCycle(),
+            $earning->getGrossAmount(),
+        );
+
+        if ($payee->getMedicareLevyExemption() === Payee::MEDICARE_LEVY_EXEMPTION_NONE) {
+            // Weekly gross must be $500 or higher, but less than the shading out point
+            if ($weeklyGross < 500 || $weeklyGross >= $this->getShadingOutPoint($payee)) {
+                return 0;
+            }
+
+            if ($weeklyGross < 625) {
+                // Final value must be negative
+                return $this->convertWeeklyTax(
+                    $payee->getPayCycle(),
+                    Math::round(
+                        ($weeklyGross - 500)
+                        * 0.1
+                    )
+                ) * -1;
+            } elseif ($weeklyGross >= 625 && $weeklyGross <= $this->getWeeklyFamilyThreshold()) {
+                // Final value must be negative
+                return $this->convertWeeklyTax(
+                    $payee->getPayCycle(),
+                    Math::round($weeklyGross * 0.02)
+                ) * -1;
+            } else {
+                // Final value must be negative
+                return $this->convertWeeklyTax(
+                    $payee->getPayCycle(),
+                    Math::round(
+                        ($this->getWeeklyFamilyThreshold() * 0.02)
+                        - (($weeklyGross - $this->getWeeklyFamilyThreshold()) * 0.08)
+                    )
+                ) * -1;
+            }
+        } elseif ($payee->getMedicareLevyExemption() === Payee::MEDICARE_LEVY_EXEMPTION_HALF) {
+            // Weekly gross must be $843 or higher, but less than the shading out point
+            if ($weeklyGross < 843 || $weeklyGross >= $this->getShadingOutPoint($payee)) {
+                return 0;
+            }
+
+            if ($weeklyGross < 1053) {
+                // Final value must be negative
+                return $this->convertWeeklyTax(
+                    $payee->getPayCycle(),
+                    Math::round(
+                        ($weeklyGross - 843.19)
+                        * 0.05
+                    )
+                ) * -1;
+            } elseif ($weeklyGross >= 1053 && $weeklyGross <= $this->getWeeklyFamilyThreshold()) {
+                // Final value must be negative
+                return $this->convertWeeklyTax(
+                    $payee->getPayCycle(),
+                    Math::round($weeklyGross * 0.01)
+                ) * -1;
+            } else {
+                // Final value must be negative
+                return $this->convertWeeklyTax(
+                    $payee->getPayCycle(),
+                    Math::round(
+                        ($this->getWeeklyFamilyThreshold() * 0.01)
+                        - (($weeklyGross - $this->getWeeklyFamilyThreshold()) * 0.04)
+                    )
+                ) * -1;
+            }
+        }
+
+        return 0;
+    }
+
+    /**
+     * Calculate the weekly family threshold, where the reduction starts to apply.
+     */
+    protected function getWeeklyFamilyThreshold(): float
+    {
+        if ($this->spouse === true && $this->children === 0) {
+            // $43,846 / 52 weeks
+            return 843.192307692;
+        }
+
+        // Up to a maximum of 10 children can be claimed
+        $children = min($this->children, 10);
+        $annualThreshold = 43846 + ($children * 4027);
+        return round($annualThreshold / 52, 2);
+    }
+
+    /**
+     * Calculate the shading out point where the reduction is no longer applicable.
+     */
+    protected function getShadingOutPoint(Payee $payee): float
+    {
+        if ($payee->getMedicareLevyExemption() === Payee::MEDICARE_LEVY_EXEMPTION_NONE) {
+            return floor(($this->getWeeklyFamilyThreshold() * 0.1) / 0.08);
+        }
+
+        return floor(($this->getWeeklyFamilyThreshold() * 0.05) / 0.04);
+    }
+}

src/Adjustments/MedicareLevyReduction.php

@@ -0,0 +1,83 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ManageIt\PaygTax\Adjustments;
+
+use ManageIt\PaygTax\Entities\Payer;
+use ManageIt\PaygTax\Entities\Payee;
+use ManageIt\PaygTax\Entities\Earning;
+use ManageIt\PaygTax\Entities\TaxAdjustment;
+use ManageIt\PaygTax\Entities\TaxScale;
+use ManageIt\PaygTax\Traits\WeeklyConversion;
+use ManageIt\PaygTax\Utilities\Date;
+use ManageIt\PaygTax\Utilities\Math;
+use ManageIt\PaygTax\Adjustments;
+
+class MedicareLevyReduction implements TaxAdjustment
+{
+    use WeeklyConversion;
+
+    /**
+     * Whether the payee is claiming to have a spouse.
+     */
+    public bool $spouse = true;
+
+    /**
+     * The number of children the payee is claiming for the Medicare Levy Reduction.
+     */
+    public int $children = 0;
+
+    public function __construct(bool $spouse = true, int $children = 0)
+    {
+        $this->spouse = $spouse;
+        $this->children = $children;
+    }
+
+    public function isEligible(Payer $payer, Payee $payee, TaxScale $taxScale, Earning $earning): bool
+    {
+        // Not eligible if you do not have a TFN
+        if ($payee->hasTfnNumber() === false) {
+            return false;
+        }
+
+        // Not eligible if you're claiming a full Medicare levy exemption
+        if ($payee->getMedicareLevyExemption() === Payee::MEDICARE_LEVY_EXEMPTION_FULL) {
+            return false;
+        }
+
+        // Not eligible if you're not claiming the tax-free threshold
+        if ($payee->claimsTaxFreeThreshold() === false) {
+            return false;
+        }
+
+        // Not eligible if you're a foreign resident or Working Holiday Maker
+        if ($payee->getResidencyStatus() !== Payee::RESIDENT) {
+            return false;
+        }
+
+        // If claiming a half Medicare levy exemption (NAT 1004 Scale 6), the payee must be claiming children - the
+        // reduction is not applicable to payees who only have a spouse
+        if ($payee->getMedicareLevyExemption() === Payee::MEDICARE_LEVY_EXEMPTION_HALF && $this->children === 0) {
+            return false;
+        }
+
+        // The payee must be claiming to have a spouse or children
+        if ($this->spouse === false && $this->children === 0) {
+            return false;
+        }
+
+        return true;
+    }
+
+    public function getAdjustmentAmount(Payer $payer, Payee $payee, TaxScale $taxScale, Earning $earning): float
+    {
+        if (Date::from($earning->getPayDate(), '2024-07-01')) {
+            $adjustment = new Adjustments\July2024\MedicareLevyReduction($this->spouse, $this->children);
+            return $adjustment->getAdjustmentAmount($payer, $payee, $taxScale, $earning);
+        }
+
+        $adjustment = new Adjustments\October2020\MedicareLevyReduction($this->spouse, $this->children);
+        return $adjustment->getAdjustmentAmount($payer, $payee, $taxScale, $earning);
+    }
+}

src/Adjustments/October2020/MedicareLevyReduction.php

@@ -7,14 +7,11 @@
 use ManageIt\PaygTax\Entities\Payer;
 use ManageIt\PaygTax\Entities\Payee;
 use ManageIt\PaygTax\Entities\Earning;
-use ManageIt\PaygTax\Entities\TaxAdjustment;
 use ManageIt\PaygTax\Entities\TaxScale;
-use ManageIt\PaygTax\TaxScales\October2020\Nat1004Scale2;
-use ManageIt\PaygTax\TaxScales\October2020\Nat1004Scale6;
 use ManageIt\PaygTax\Traits\WeeklyConversion;
 use ManageIt\PaygTax\Utilities\Math;
 
-class MedicareLevyReduction implements TaxAdjustment
+class MedicareLevyReduction
 {
     use WeeklyConversion;
 
@@ -34,38 +31,14 @@ public function __construct(bool $spouse = true, int $children = 0)
         $this->children = $children;
     }
 
-    public function isEligible(Payer $payer, Payee $payee, TaxScale $taxScale, Earning $earning): bool
-    {
-        // The tax scale must be either of the following tax scales
-        if (
-            $taxScale instanceof Nat1004Scale2 === false
-            && $taxScale instanceof Nat1004Scale6 === false
-        ) {
-            return false;
-        }
-
-        // The payee must be claiming to have a spouse or children
-        if ($this->spouse === false && $this->children === 0) {
-            return false;
-        }
-
-        // If claiming a half Medicare levy exemption (NAT 1004 Scale 6), the payee must be claiming children - the
-        // reduction is not applicable to payees who only have a spouse
-        if ($taxScale instanceof Nat1004Scale6 && $this->children === 0) {
-            return false;
-        }
-
-        return true;
-    }
-
     public function getAdjustmentAmount(Payer $payer, Payee $payee, TaxScale $taxScale, Earning $earning): float
     {
         $weeklyGross = $this->getWeeklyGross(
             $payee->getPayCycle(),
             $earning->getGrossAmount(),
         );
 
-        if ($taxScale instanceof Nat1004Scale2) {
+        if ($payee->getMedicareLevyExemption() === Payee::MEDICARE_LEVY_EXEMPTION_NONE) {
             // Weekly gross must be $438 or higher, but less than the shading out point
             if ($weeklyGross < 438 || $weeklyGross >= $this->getShadingOutPoint()) {
                 return 0;
@@ -96,7 +69,7 @@ public function getAdjustmentAmount(Payer $payer, Payee $payee, TaxScale $taxSca
                     )
                 ) * -1;
             }
-        } elseif ($taxScale instanceof Nat1004Scale6) {
+        } elseif ($payee->getMedicareLevyExemption() === Payee::MEDICARE_LEVY_EXEMPTION_HALF) {
             // Weekly gross must be $739 or higher, but less than the shading out point
             if ($weeklyGross < 739 || $weeklyGross >= $this->getShadingOutPoint()) {
                 return 0;