Updated Price Model TaxIncl methods & Cart Item TaxIncl properties to actually provide Tax inclusive values.

packages/core/database/migrations/2026_04_25_100000_add_tax_zone_id_to_carts_table.php

@@ -0,0 +1,28 @@
+<?php
+
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+use Lunar\Base\Migration;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table($this->prefix.'carts', function (Blueprint $table) {
+            $table->foreignId('tax_zone_id')->after('channel_id')
+                ->nullable()
+                ->constrained($this->prefix.'tax_zones')
+                ->nullOnDelete();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table($this->prefix.'carts', function (Blueprint $table) {
+            if ($this->canDropForeignKeys()) {
+                $table->dropForeign(['tax_zone_id']);
+            }
+            $table->dropColumn('tax_zone_id');
+        });
+    }
+};

packages/core/src/Actions/Carts/CalculateLineSubtotal.php

@@ -45,7 +45,7 @@ public function execute(
             );
 
             $priceInclTax = new Price(
-                $priceResponse->matched->priceIncTax()->value,
+                $priceResponse->matched->priceIncTax($cart->taxZone)->value,
                 $cart->currency,
                 $purchasable->getUnitQuantity()
             );

packages/core/src/Base/TaxDriver.php

@@ -5,6 +5,7 @@
 use Lunar\Base\ValueObjects\Cart\TaxBreakdown;
 use Lunar\Models\Contracts\CartLine;
 use Lunar\Models\Contracts\Currency;
+use Lunar\Models\Contracts\TaxZone;
 
 interface TaxDriver
 {
@@ -33,6 +34,15 @@ public function setPurchasable(Purchasable $purchasable): self;
      */
     public function setCartLine(CartLine $cartLine): self;
 
+    /**
+     * Set a tax zone override.
+     *
+     * When provided, this zone is used directly instead of resolving one from the shipping address, allowing
+     * the developer to handle cases like taxation on IP address basis. Just set the tax zone as and let it
+     * flow smoothly.
+     */
+    public function setTaxZone(?TaxZone $taxZone = null): self;
+
     /**
      * Return the tax breakdown from a given sub total.
      *

packages/core/src/Drivers/SystemTaxDriver.php

@@ -11,6 +11,7 @@
 use Lunar\DataTypes\Price;
 use Lunar\Models\Contracts\CartLine;
 use Lunar\Models\Contracts\Currency;
+use Lunar\Models\Contracts\TaxZone as TaxZoneContract;
 use Lunar\Models\TaxZone;
 use Spatie\LaravelBlink\BlinkFacade as Blink;
 
@@ -41,6 +42,12 @@ class SystemTaxDriver implements TaxDriver
      */
     protected ?CartLine $cartLine = null;
 
+    /**
+     * An optional tax zone override supplied at the cart level.
+     * When set this takes precedence over the address-derived zone.
+     */
+    protected ?TaxZoneContract $taxZone = null;
+
     /**
      * {@inheritDoc}
      */
@@ -91,12 +98,22 @@ public function setCartLine(CartLine $cartLine): self
         return $this;
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    public function setTaxZone(?TaxZoneContract $taxZone = null): self
+    {
+        $this->taxZone = $taxZone;
+
+        return $this;
+    }
+
     /**
      * {@inheritDoc}
      */
     public function getBreakdown($subTotal): TaxBreakdown
     {
-        $taxZone = app(GetTaxZone::class)->execute($this->shippingAddress);
+        $taxZone = $this->taxZone ?? app(GetTaxZone::class)->execute($this->shippingAddress);
         $taxClass = $this->purchasable->getTaxClass();
 
         $taxAmounts = Blink::once('tax_zone_rates_'.$taxZone->id.'_'.$taxClass->id, function () use ($taxClass, $taxZone) {

packages/core/src/Models/Cart.php

@@ -42,6 +42,7 @@
 use Lunar\Exceptions\FingerprintMismatchException;
 use Lunar\Facades\DB;
 use Lunar\Facades\ShippingManifest;
+use Lunar\Models\Contracts\TaxZone as TaxZoneContract;
 use Lunar\Pipelines\Cart\Calculate;
 use Lunar\Validation\Cart\ValidateCartForOrderCreation;
 use Lunar\Validation\CartLine\CartLineStock;
@@ -53,6 +54,7 @@
  * @property ?int $merged_id
  * @property int $currency_id
  * @property int $channel_id
+ * @property ?int $tax_zone_id
  * @property ?int $order_id
  * @property ?string $coupon_code
  * @property ?Carbon $completed_at
@@ -230,6 +232,11 @@ public function customer(): BelongsTo
         return $this->belongsTo(Customer::modelClass());
     }
 
+    public function taxZone(): BelongsTo
+    {
+        return $this->belongsTo(TaxZone::modelClass());
+    }
+
     public function scopeUnmerged(Builder $query): Builder
     {
         return $query->whereNull('merged_id');
@@ -493,8 +500,12 @@ public function addAddress(array|Addressable $address, string $type, bool $refre
             ->then(fn () => $refresh ? $this->refresh()->recalculate() : $this);
     }
 
-    public function setShippingAddress(array|Addressable $address): Cart
+    public function setShippingAddress(array|Addressable $address, bool $clearTaxZone = true): Cart
     {
+        if ($clearTaxZone && $this->tax_zone_id) {
+            $this->taxZone()->dissociate()->save();
+        }
+
         return $this->addAddress($address, 'shipping');
     }
 
@@ -622,4 +633,28 @@ public function getEstimatedShipping(array $params, bool $setOverride = false):
 
         return $option;
     }
+
+    /**
+     * Set the tax zone override for this cart.
+     *
+     * When set, all tax calculations use this zone instead of resolving one from the shipping address.
+     * Pass null to clear the override and fall back to the address-derived (or default) zone.
+     * Pass `$refresh = false` to skip persistence and recalculation (useful for previewing without writing).
+     */
+    public function setTaxZone(?TaxZoneContract $taxZone, bool $refresh = true): Cart
+    {
+        if ($taxZone) {
+            $this->taxZone()->associate($taxZone);
+        } else {
+            $this->taxZone()->dissociate();
+        }
+
+        if (! $refresh) {
+            return $this;
+        }
+
+        $this->save();
+
+        return $this->refresh()->recalculate();
+    }
 }

packages/core/src/Models/CartLine.php

@@ -41,6 +41,7 @@ class CartLine extends BaseModel implements Contracts\CartLine
      */
     public $cachableProperties = [
         'unitPrice',
+        'unitPriceInclTax',
         'subTotal',
         'discountTotal',
         'taxAmount',

packages/core/src/Models/Contracts/Cart.php

@@ -139,8 +139,12 @@ public function addAddress(array|Addressable $address, string $type, bool $refre
 
     /**
      * Set the shipping address.
+     *
+     * By default any tax-zone override set on the cart is cleared, since
+     * the address is now the authoritative source for tax-zone resolution.
+     * Pass `$clearTaxZone = false` to keep a previously-pinned zone.
      */
-    public function setShippingAddress(array|Addressable $address): \Lunar\Models\Cart;
+    public function setShippingAddress(array|Addressable $address, bool $clearTaxZone = true): \Lunar\Models\Cart;
 
     /**
      * Set the billing address.
@@ -188,4 +192,13 @@ public function checkFingerprint(string $fingerprint): bool;
      * Return the estimated shipping cost for a cart.
      */
     public function getEstimatedShipping(array $params, bool $setOverride = false): ?ShippingOption;
+
+    /**
+     * Set the tax zone override for this cart.
+     *
+     * When set, all tax calculations use this zone instead of resolving one
+     * from the shipping address. Pass null to clear the override.
+     * Pass `$refresh = false` to skip persistence and recalculation.
+     */
+    public function setTaxZone(?TaxZone $taxZone, bool $refresh = true): \Lunar\Models\Cart;
 }

packages/core/src/Models/Contracts/Price.php

@@ -4,6 +4,7 @@
 
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
 use Illuminate\Database\Eloquent\Relations\MorphTo;
+use Lunar\Models\Contracts\TaxZone;
 
 interface Price
 {
@@ -24,11 +25,22 @@ public function customerGroup(): BelongsTo;
 
     /**
      * Return the price exclusive of tax.
+     *
+     * @param  TaxZone|null  $taxZone
      */
-    public function priceExTax(): \Lunar\DataTypes\Price;
+    public function priceExTax(?TaxZone $taxZone = null): \Lunar\DataTypes\Price;
 
     /**
      * Return the price inclusive of tax.
+     *
+     * @param  TaxZone|null  $taxZone
      */
-    public function priceIncTax(): int|\Lunar\DataTypes\Price;
+    public function priceIncTax(?TaxZone $taxZone = null): int|\Lunar\DataTypes\Price;
+
+    /**
+     * Return the compare price inclusive of tax.
+     *
+     * @param  TaxZone|null  $taxZone
+     */
+    public function comparePriceIncTax(?TaxZone $taxZone = null): int|\Lunar\DataTypes\Price;
 }

packages/core/src/Models/Price.php

@@ -10,6 +10,7 @@
 use Lunar\Base\Casts\Price as CastsPrice;
 use Lunar\Base\Traits\HasMacros;
 use Lunar\Database\Factories\PriceFactory;
+use Lunar\Models\Contracts\TaxZone as TaxZoneContract;
 use Spatie\LaravelBlink\BlinkFacade as Blink;
 
 /**
@@ -76,59 +77,71 @@ public function customerGroup(): BelongsTo
 
     /**
      * Return the price exclusive of tax.
+     *
+     * @param  TaxZone|null  $taxZone  Optional override for the tax zone. Falls back to the store's default zone.
      */
-    public function priceExTax(): \Lunar\DataTypes\Price
+    public function priceExTax(?TaxZoneContract $taxZone = null): \Lunar\DataTypes\Price
     {
         if (! prices_inc_tax()) {
             return $this->price;
         }
 
         $priceExTax = clone $this->price;
 
-        $priceExTax->value = (int) round($priceExTax->value / (1 + $this->getPriceableTaxRate()));
+        $priceExTax->value = (int) round($priceExTax->value / (1 + $this->getPriceableTaxRate($taxZone)));
 
         return $priceExTax;
     }
 
     /**
      * Return the price inclusive of tax.
+     *
+     * @param  TaxZone|null  $taxZone  Optional override for the tax zone.
      */
-    public function priceIncTax(): int|\Lunar\DataTypes\Price
+    public function priceIncTax(?TaxZoneContract $taxZone = null): int|\Lunar\DataTypes\Price
     {
         if (prices_inc_tax()) {
             return $this->price;
         }
 
         $priceIncTax = clone $this->price;
-        $priceIncTax->value = (int) round($priceIncTax->value * (1 + $this->getPriceableTaxRate()));
+        $priceIncTax->value = (int) round($priceIncTax->value * (1 + $this->getPriceableTaxRate($taxZone)));
 
         return $priceIncTax;
     }
 
     /**
      * Return the compare price inclusive of tax.
+     *
+     * @param  TaxZone|null  $taxZone  Optional override for the tax zone.
      */
-    public function comparePriceIncTax(): int|\Lunar\DataTypes\Price
+    public function comparePriceIncTax(?TaxZoneContract $taxZone = null): int|\Lunar\DataTypes\Price
     {
         if (prices_inc_tax()) {
             return $this->compare_price;
         }
 
         $comparePriceIncTax = clone $this->compare_price;
-        $comparePriceIncTax->value = (int) round($comparePriceIncTax->value * (1 + $this->getPriceableTaxRate()));
+        $comparePriceIncTax->value = (int) round($comparePriceIncTax->value * (1 + $this->getPriceableTaxRate($taxZone)));
 
         return $comparePriceIncTax;
     }
 
     /**
-     * Return the total tax rate amount within the predefined tax zone for the related priceable
+     * Return the total tax rate (as a decimal, e.g. 0.20 = 20%) for the given tax zone
+     * combined with the priceable's own tax class.
+     *
+     * Tax zone resolution: explicit param → store default zone.
+     * Results are memoised per "{classId}_{zoneId}" so unrelated combinations never collide.
      */
-    protected function getPriceableTaxRate(): int|float
+    protected function getPriceableTaxRate(?TaxZoneContract $taxZone = null): int|float
     {
-        return Blink::once('price_tax_rate_'.$this->priceable->getTaxClass()->id, function () {
-            $taxZone = TaxZone::where('default', '=', 1)->first();
+        $taxClass = $this->priceable->getTaxClass();
+        $taxZone ??= Blink::once('lunar_default_tax_zone', fn () => TaxZone::where('default', '=', 1)->first());
+        $cacheKey = 'price_tax_rate_'.$taxClass->id.'_'.($taxZone?->id ?? 'none');
 
-            if ($taxZone && ! is_null($taxClass = $this->priceable->getTaxClass())) {
+        return Blink::once($cacheKey, function () use ($taxClass, $taxZone) {
+            if ($taxZone && $taxClass) {
                 return $taxClass->taxRateAmounts
                     ->whereIn('tax_rate_id', $taxZone->taxRates->pluck('id'))
                     ->sum('percentage') / 100;

packages/core/src/Pipelines/Cart/CalculateTax.php

@@ -37,6 +37,7 @@ public function handle(CartContract $cart, Closure $next): mixed
                 ->setCurrency($cart->currency)
                 ->setPurchasable($cartLine->purchasable)
                 ->setCartLine($cartLine)
+                ->setTaxZone($cart->taxZone)
                 ->getBreakdown($subTotal);
 
             $taxBreakDownAmounts = $taxBreakDownAmounts->merge(
@@ -70,6 +71,7 @@ public function handle(CartContract $cart, Closure $next): mixed
             $shippingTax = Taxes::setShippingAddress($cart->shippingAddress)
                 ->setCurrency($cart->currency)
                 ->setPurchasable($shippingOption)
+                ->setTaxZone($cart->taxZone)
                 ->getBreakdown($shippingSubTotal);
 
             $shippingTaxTotal = $shippingTax->amounts->sum('price.value');

packages/core/src/Pipelines/CartLine/GetUnitPrice.php

@@ -47,7 +47,7 @@ public function handle(CartLineContract $cartLine, Closure $next)
         );
 
         $cartLine->unitPriceInclTax = new Price(
-            $priceResponse->matched->priceIncTax()->value,
+            $priceResponse->matched->priceIncTax($cart->taxZone)->value,
             $cart->currency,
             $purchasable->getUnitQuantity()
         );