diff --git a/app/models/spree/tax_rate.rb b/app/models/spree/tax_rate.rb
index f0a7be6e11..6a60d9e988 100644
--- a/app/models/spree/tax_rate.rb
+++ b/app/models/spree/tax_rate.rb
@@ -117,25 +117,6 @@ module Spree
       Zone.default_tax&.contains?(order.tax_zone) || order.tax_zone == zone
     end
 
-    # Manually apply a TaxRate to a particular amount. TaxRates normally compute against
-    # LineItems or Orders, so we mock out a line item here to fit the interface
-    # that our calculator (usually DefaultTax) expects.
-    def compute_tax(amount)
-      line_item = LineItem.new quantity: 1
-      line_item.tax_category = tax_category
-      line_item.define_singleton_method(:price) { amount }
-
-      # Tax on adjustments (represented by the included_tax field) is always inclusive of
-      # tax. However, there's nothing to stop an admin from setting one up with a tax rate
-      # that's marked as not inclusive of tax, and that would result in the DefaultTax
-      # calculator generating a slightly incorrect value. Therefore, we treat the tax
-      # rate as inclusive of tax for the calculations below, regardless of its original
-      # setting.
-      with_tax_included_in_price do
-        calculator.compute line_item
-      end
-    end
-
     private
 
     def create_label(adjustment_amount)