diff --git a/apps/web/__tests__/support/pageObjects/CheckoutPageObject.ts b/apps/web/__tests__/support/pageObjects/CheckoutPageObject.ts
index b57470a9d..808f996aa 100644
--- a/apps/web/__tests__/support/pageObjects/CheckoutPageObject.ts
+++ b/apps/web/__tests__/support/pageObjects/CheckoutPageObject.ts
@@ -29,6 +29,10 @@ export class CheckoutPageObject extends PageObject {
     return cy.getByTestId('save-address-2');
   }
 
+  get saveBilling() {
+    return cy.getByTestId('save-address-1');
+  }
+
   get contactInformationFormSaveButton() {
     return cy.getByTestId('contact-information-save-button');
   }
@@ -49,6 +53,11 @@ export class CheckoutPageObject extends PageObject {
     return cy.getByTestId('checkout-edit-address-modal');
   }
 
+   editBillingAddress() {
+    cy.getByTestId('edit-address-1').click();
+    return this;
+  }
+
   get thankYouBanner() {
     return cy.getByTestId('success-header');
   }
@@ -190,7 +199,7 @@ export class CheckoutPageObject extends PageObject {
 
   shouldShowShippingAsBillingText() {
     this.shippingAsBillingText.contains('Same as shipping address');
-    return this; 
+    return this;
   }
 
   fillCreditCardForm() {
diff --git a/apps/web/__tests__/test/feature/checkout-addresses.cy.ts b/apps/web/__tests__/test/feature/checkout-addresses.cy.ts
index f6e5e3db7..7aba00185 100644
--- a/apps/web/__tests__/test/feature/checkout-addresses.cy.ts
+++ b/apps/web/__tests__/test/feature/checkout-addresses.cy.ts
@@ -29,4 +29,22 @@ describe('Checkout Addresses', () => {
         .fillShippingAddressForm()
         .shouldShowShippingAsBillingText();
   });
+
+  it('should be able to edit the billing address as a guest user if selected same as shipping', () => {
+    homePage.goToCategory();
+    productListPage.addToCart()
+
+    cart.openCart();
+    checkout
+        .goToCheckout()
+        .goToGuestCheckout()
+        .fillContactInformationForm()
+        .fillShippingAddressForm()
+        .shouldShowShippingAsBillingText()
+        .editBillingAddress();
+    checkout.firstNameInput.clear();
+    checkout.firstNameInput.type('John Guest Edit');
+    checkout.saveBilling.click({ force: true });
+    cy.get('#billing-address').should('contain', 'John Guest Edit');
+  });
 });
diff --git a/apps/web/components/AddressContainer/AddressContainer.vue b/apps/web/components/AddressContainer/AddressContainer.vue
index 15a65bcaa..77437d0ec 100644
--- a/apps/web/components/AddressContainer/AddressContainer.vue
+++ b/apps/web/components/AddressContainer/AddressContainer.vue
@@ -28,7 +28,12 @@
           class="ml-2"
           :label="!editing && !showNewForm && !disabled ? t('editAddress') : ''"
         >
-          <UiButton @click="edit(checkoutAddress)" :disabled="formIsLoading || disabled" variant="secondary">
+          <UiButton
+            @click="edit(checkoutAddress)"
+            :disabled="formIsLoading || disabled"
+            variant="secondary"
+            :data-testid="'edit-address-' + type"
+          >
             <template v-if="!editing && !showNewForm">{{ t('contactInfo.edit') }}</template>
             <SfIconClose v-else />
           </UiButton>
diff --git a/apps/web/components/AddressForm/AddressForm.vue b/apps/web/components/AddressForm/AddressForm.vue
index 176597598..5f2385393 100644
--- a/apps/web/components/AddressForm/AddressForm.vue
+++ b/apps/web/components/AddressForm/AddressForm.vue
@@ -112,15 +112,9 @@ const { type, savedAddress: propertySavedAddress, useAsShippingDefault = true }
 
 const { loading: loadBilling } = useAddress(AddressType.Billing);
 const { loading: loadShipping } = useAddress(AddressType.Shipping);
-const {
-  useGeoRegulatedCountries,
-  default: defaultCountries,
-  geoRegulated: geoRegulatedCountries,
-} = useAggregatedCountries();
+const { billingCountries, default: defaultCountries } = useAggregatedCountries();
 
-const countries = computed(() =>
-  type === AddressType.Billing && useGeoRegulatedCountries ? geoRegulatedCountries.value : defaultCountries.value,
-);
+const countries = computed(() => (type === AddressType.Billing ? billingCountries.value : defaultCountries.value));
 const isCartUpdateLoading = computed(() => loadBilling.value || loadShipping.value);
 const useAsShippingAddress = ref(useAsShippingDefault);
 const savedAddress = propertySavedAddress || ({} as Address);
diff --git a/apps/web/components/AddressFormBilling/AddressFormBilling.vue b/apps/web/components/AddressFormBilling/AddressFormBilling.vue
index 25fd4c62e..febebf06b 100644
--- a/apps/web/components/AddressFormBilling/AddressFormBilling.vue
+++ b/apps/web/components/AddressFormBilling/AddressFormBilling.vue
@@ -119,7 +119,7 @@
         :invalid="Boolean(errors['country'])"
       >
         <option
-          v-for="(billingCountry, index) in countries"
+          v-for="(billingCountry, index) in billingCountries"
           :key="`billing-country-${index}`"
           :value="billingCountry.id.toString()"
         >
@@ -139,17 +139,13 @@ import { type Address, AddressType, userAddressGetters } from '@plentymarkets/sh
 
 const { address, addAddress = false } = defineProps<AddressFormProps>();
 
+const { isGuest } = useCustomer();
+const { shippingAsBilling } = useShippingAsBilling();
 const { hasCompany, addressToSave, save: saveAddress, validationSchema } = useAddressForm(AddressType.Billing);
 const { addresses: billingAddresses } = useAddressStore(AddressType.Billing);
 const { set: setCheckoutAddress } = useCheckoutAddress(AddressType.Billing);
 const { defineField, errors, setValues, validate, handleSubmit } = useForm({ validationSchema: validationSchema });
-const {
-  useGeoRegulatedCountries,
-  default: defaultCountries,
-  geoRegulated: geoRegulatedCountries,
-} = useAggregatedCountries();
-
-const countries = computed(() => (useGeoRegulatedCountries ? geoRegulatedCountries.value : defaultCountries.value));
+const { billingCountries } = useAggregatedCountries();
 
 const [firstName, firstNameAttributes] = defineField('firstName');
 const [lastName, lastNameAttributes] = defineField('lastName');
@@ -170,18 +166,23 @@ if (!addAddress) {
   }
 }
 
+const guestHasShippingAsBilling = isGuest.value && shippingAsBilling.value;
+
 const syncCheckoutAddress = async () => {
   await setCheckoutAddress(
-    addAddress
+    addAddress || guestHasShippingAsBilling
       ? (billingAddresses.value[0] as Address)
       : (userAddressGetters.getDefault(billingAddresses.value) as Address),
     !addAddress,
   );
+
+  if (guestHasShippingAsBilling) shippingAsBilling.value = false;
 };
 
 const submitForm = handleSubmit((billingAddressForm) => {
   addressToSave.value = billingAddressForm as Address;
 
+  if (guestHasShippingAsBilling && !addAddress) delete addressToSave.value?.id;
   if (addAddress) addressToSave.value.primary = true;
   if (!hasCompany.value) {
     addressToSave.value.companyName = '';
diff --git a/apps/web/composables/useAggregatedCountries/types.ts b/apps/web/composables/useAggregatedCountries/types.ts
index 632816117..6a1c7f666 100644
--- a/apps/web/composables/useAggregatedCountries/types.ts
+++ b/apps/web/composables/useAggregatedCountries/types.ts
@@ -1,4 +1,8 @@
-import { type AggregatedCountries } from '@plentymarkets/shop-api';
+import {
+  type ActiveShippingCountry,
+  type GeoRegulatedCountry,
+  type AggregatedCountries,
+} from '@plentymarkets/shop-api';
 
 export interface UseAggregatedCountriesState {
   default: AggregatedCountries['default'];
@@ -14,6 +18,7 @@ export interface UseAggregatedCountries {
   loading: Readonly<Ref<boolean>>;
   fetchAggregatedCountries: FetchAggregatedCountries;
   useGeoRegulatedCountries: boolean;
+  billingCountries: ComputedRef<(ActiveShippingCountry | GeoRegulatedCountry)[]>;
 }
 
 export type UseAggregatedCountriesReturn = () => UseAggregatedCountries;
diff --git a/apps/web/composables/useAggregatedCountries/useAggregatedCountries.ts b/apps/web/composables/useAggregatedCountries/useAggregatedCountries.ts
index 19500fa5f..e47183d8d 100644
--- a/apps/web/composables/useAggregatedCountries/useAggregatedCountries.ts
+++ b/apps/web/composables/useAggregatedCountries/useAggregatedCountries.ts
@@ -3,8 +3,9 @@ import { type UseAggregatedCountriesReturn, UseAggregatedCountriesState, type Fe
 
 /**
  * @description Composable for getting `AggregatedCountries`:
- * - Active shipping countries
+ * - Default shipping countries
  * - EU geo-regulated countries
+ * - A combined list of countries
  *
  * @example
  * ``` ts
@@ -14,6 +15,7 @@ import { type UseAggregatedCountriesReturn, UseAggregatedCountriesState, type Fe
  *  loading,
  *  fetchAggregatedCountries,
  *  useGeoRegulatedCountries,
+ *  billingCountries,
  * } = useAggregatedCountries();
  * ```
  */
@@ -43,9 +45,20 @@ export const useAggregatedCountries: UseAggregatedCountriesReturn = () => {
 
   const useGeoRegulatedCountries = state.value.geoRegulated.length > 0;
 
+  const billingCountries = computed(() => {
+    if (!useGeoRegulatedCountries) return state.value.default;
+
+    const uniqueCountries = new Map(
+      [...state.value.default, ...state.value.geoRegulated].map((country) => [country.id, country]),
+    );
+
+    return [...uniqueCountries.values()].sort((first, second) => first.id - second.id);
+  });
+
   return {
     fetchAggregatedCountries,
     useGeoRegulatedCountries,
+    billingCountries,
     ...toRefs(state.value),
   };
 };
diff --git a/docs/changelog/changelog_en.md b/docs/changelog/changelog_en.md
index 1a5945edd..6494a40d8 100644
--- a/docs/changelog/changelog_en.md
+++ b/docs/changelog/changelog_en.md
@@ -28,6 +28,7 @@
 
 ### 🩹 Fixed
 
+- Addressed an unhandled scenario in which a guest user attempts to modify their billing address while using the same address for shipping.
 - Fixed an issue where increasing the quantity beyond maximum stock would clear the cart.
 - Removed the "Add to Cart" notification from item and category pages when the quick checkout modal is not present.
 - Improved accessibility for the cart and wishlist pages by increasing the font size.