diff --git a/app/models/enterprise_fee_adjustments.rb b/app/models/enterprise_fee_adjustments.rb
index a31c768d6d8..96798091914 100644
--- a/app/models/enterprise_fee_adjustments.rb
+++ b/app/models/enterprise_fee_adjustments.rb
@@ -8,18 +8,10 @@ def initialize(adjustments)
   end
 
   def total_additional_tax
-    @adjustments.reduce(0.0) do |sum, enterprise_fee|
-      sum += enterprise_fee.additional_tax_total if enterprise_fee&.adjustments
-
-      sum
-    end
+    @adjustments.sum { |enterprise_fee| enterprise_fee.additional_tax_total.to_f }
   end
 
   def total_included_tax
-    @adjustments.reduce(0.0) do |sum, enterprise_fee|
-      sum += enterprise_fee.included_tax_total if enterprise_fee&.adjustments
-
-      sum
-    end
+    @adjustments.sum { |enterprise_fee| enterprise_fee.included_tax_total.to_f }
   end
 end
diff --git a/spec/models/enterprise_fee_adjustments_spec.rb b/spec/models/enterprise_fee_adjustments_spec.rb
index 3e2a5f6fb24..8e00118b110 100644
--- a/spec/models/enterprise_fee_adjustments_spec.rb
+++ b/spec/models/enterprise_fee_adjustments_spec.rb
@@ -5,10 +5,14 @@
 describe EnterpriseFeeAdjustments do
   let(:tax_rate) { create(:tax_rate, amount: 0.1) }
   let(:line_item) { create(:line_item) }
+  let(:line_item2) { create(:line_item) }
   let(:enterprise_fee) { create(:enterprise_fee, tax_category: tax_rate.tax_category) }
   let(:fee_adjustment) {
     create( :adjustment, originator: enterprise_fee, adjustable: line_item, state: "closed")
   }
+  let(:fee_adjustment2) {
+    create( :adjustment, originator: enterprise_fee, adjustable: line_item, state: "closed")
+  }
 
   describe "#total_additional_tax" do
     it "calculates total tax" do
@@ -20,10 +24,26 @@
         state: "closed",
         included: false
       )
+      create(
+        :adjustment,
+        originator: tax_rate,
+        adjustable: fee_adjustment2,
+        amount: 5.0,
+        state: "closed",
+        included: false
+      )
+
+      enterprise_fee_adjustments = EnterpriseFeeAdjustments.new([fee_adjustment, fee_adjustment2])
 
-      enterprise_fee_adjustments = EnterpriseFeeAdjustments.new([fee_adjustment])
+      expect(enterprise_fee_adjustments.total_additional_tax).to eq(15.0)
+    end
 
-      expect(enterprise_fee_adjustments.total_additional_tax).to eq(10.0)
+    context "with no tax adjustment" do
+      it "returns 0.0" do
+        enterprise_fee_adjustments = EnterpriseFeeAdjustments.new([fee_adjustment])
+
+        expect(enterprise_fee_adjustments.total_additional_tax).to eq(0.0)
+      end
     end
 
     context "with tax included in price" do
@@ -54,10 +74,26 @@
         state: "closed",
         included: true
       )
+      create(
+        :adjustment,
+        originator: tax_rate,
+        adjustable: fee_adjustment2,
+        amount: 5.0,
+        state: "closed",
+        included: true
+      )
 
-      enterprise_fee_adjustments = EnterpriseFeeAdjustments.new([fee_adjustment])
+      enterprise_fee_adjustments = EnterpriseFeeAdjustments.new([fee_adjustment, fee_adjustment2])
 
-      expect(enterprise_fee_adjustments.total_included_tax).to eq(10.0)
+      expect(enterprise_fee_adjustments.total_included_tax).to eq(15.0)
+    end
+
+    context "with no tax adjustment" do
+      it "returns 0.0" do
+        enterprise_fee_adjustments = EnterpriseFeeAdjustments.new([fee_adjustment])
+
+        expect(enterprise_fee_adjustments.total_additional_tax).to eq(0.0)
+      end
     end
 
     context "with tax excluded from price" do