diff --git a/changelog/60_UNRELEASED_2020-xx-xx.md b/changelog/60_UNRELEASED_2020-xx-xx.md
index eccd940d..961a064d 100644
--- a/changelog/60_UNRELEASED_2020-xx-xx.md
+++ b/changelog/60_UNRELEASED_2020-xx-xx.md
@@ -30,6 +30,7 @@ _- (Because the stock quantity unit is now the base for everything, it cannot be
 
 ### Stock improvements/fixes
 - When creating a quantity unit conversion it's now possible to automatically create the inverse conversion (thanks @kriddles)
+- On purchase there is now a warning shown, when the best before date of the purchased product is earlier than the next best before date in stock (enabled by default, can be disabled by a new stock setting (top right corner settings menu))
 - Optimized/clarified what the total/unit price is on the purchase page (thanks @kriddles)
 - On the purchase page the amount field is now displayed above/before the best before date for better `TAB` handling (thanks @kriddles)
 - Changed that when `FEATURE_FLAG_STOCK_BEST_BEFORE_DATE_TRACKING` is disabled, products now get internally a best before of "never expires" (aka `2999-12-31`) instead of today (thanks @kriddles)
diff --git a/config-dist.php b/config-dist.php
index 1c5f0c32..ffc69de2 100644
--- a/config-dist.php
+++ b/config-dist.php
@@ -120,6 +120,7 @@ DefaultUserSetting('scan_mode_consume_enabled', false);
 DefaultUserSetting('scan_mode_purchase_enabled', false);
 DefaultUserSetting('show_icon_on_stock_overview_page_when_product_is_on_shopping_list', true);
 DefaultUserSetting('show_purchased_date_on_purchase', false); // Wheter the purchased date should be editable on purchase (defaults to today otherwise)
+DefaultUserSetting('show_warning_on_purchase_when_best_before_date_is_earlier_than_next', true); // Show a warning on purchase when the best before date of the purchased product is earlier than the next best before date in stock
 
 // Shopping list settings
 DefaultUserSetting('shopping_list_to_stock_workflow_auto_submit_when_prefilled', false); // Automatically do the booking using the last price and the amount of the shopping list item, if the product has "Default best before days" set
diff --git a/localization/strings.pot b/localization/strings.pot
index 1325037d..2559fea6 100644
--- a/localization/strings.pot
+++ b/localization/strings.pot
@@ -1924,3 +1924,9 @@ msgstr ""
 
 msgid "This is the default quantity unit used when adding this product to the shopping list"
 msgstr ""
+
+msgid "Show a warning when the best before date of the purchased product is earlier than the next best before date in stock"
+msgstr ""
+
+msgid "There are items in stock which expire earlier"
+msgstr ""
diff --git a/public/viewjs/purchase.js b/public/viewjs/purchase.js
index ba9424e3..2ca2745e 100644
--- a/public/viewjs/purchase.js
+++ b/public/viewjs/purchase.js
@@ -1,4 +1,6 @@
-$('#save-purchase-button').on('click', function(e)
+var CurrentProductDetails;
+
+$('#save-purchase-button').on('click', function(e)
 {
 	e.preventDefault();
 
@@ -97,6 +99,14 @@
 						toastr.success(successMessage);
 						Grocy.Components.ProductPicker.FinishFlow();
 
+						if (Grocy.FeatureFlags.GROCY_FEATURE_FLAG_STOCK_BEST_BEFORE_DATE_TRACKING && BoolVal(Grocy.UserSettings.show_warning_on_purchase_when_best_before_date_is_earlier_than_next))
+						{
+							if (moment(jsonData.best_before_date).isBefore(CurrentProductDetails.next_best_before_date))
+							{
+								toastr.warning(__t("There are items in stock which expire earlier"));
+							}
+						}
+
 						Grocy.Components.ProductAmountPicker.Reset();
 						$("#display_amount").attr("min", "1");
 						$("#display_amount").attr("step", "1");
@@ -162,6 +172,8 @@ if (Grocy.Components.ProductPicker !== undefined)
 			Grocy.Api.Get('stock/products/' + productId,
 				function(productDetails)
 				{
+					CurrentProductDetails = productDetails;
+
 					Grocy.Components.ProductAmountPicker.Reload(productDetails.product.id, productDetails.quantity_unit_stock.id);
 					Grocy.Components.ProductAmountPicker.SetQuantityUnit(productDetails.default_quantity_unit_purchase.id);
 					$('#display_amount').val(parseFloat(Grocy.UserSettings.stock_default_purchase_amount).toLocaleString({ minimumFractionDigits: 0, maximumFractionDigits: Grocy.UserSettings.stock_decimal_places_amounts }));
diff --git a/public/viewjs/stocksettings.js b/public/viewjs/stocksettings.js
index 9d355bcf..48497f43 100644
--- a/public/viewjs/stocksettings.js
+++ b/public/viewjs/stocksettings.js
@@ -15,3 +15,8 @@ if (BoolVal(Grocy.UserSettings.show_purchased_date_on_purchase))
 {
 	$("#show_purchased_date_on_purchase").prop("checked", true);
 }
+
+if (BoolVal(Grocy.UserSettings.show_warning_on_purchase_when_best_before_date_is_earlier_than_next))
+{
+	$("#show_warning_on_purchase_when_best_before_date_is_earlier_than_next").prop("checked", true);
+}
diff --git a/views/stocksettings.blade.php b/views/stocksettings.blade.php
index 705a8380..1b296599 100644
--- a/views/stocksettings.blade.php
+++ b/views/stocksettings.blade.php
@@ -104,6 +104,19 @@
 			</div>
 		</div>
 
+		<div class="form-group">
+			<div class="custom-control custom-checkbox">
+				<input type="checkbox"
+					class="form-check-input custom-control-input user-setting-control"
+					id="show_warning_on_purchase_when_best_before_date_is_earlier_than_next"
+					data-setting-key="show_warning_on_purchase_when_best_before_date_is_earlier_than_next">
+				<label class="form-check-label custom-control-label"
+					for="show_warning_on_purchase_when_best_before_date_is_earlier_than_next">
+					{{ $__t('Show a warning when the best before date of the purchased product is earlier than the next best before date in stock') }}
+				</label>
+			</div>
+		</div>
+
 		<h4 class="mt-2">{{ $__t('Consume') }}</h4>
 		@include('components.numberpicker', array(
 		'id' => 'stock_default_consume_amount',