diff --git a/src/fetch/payouts.py b/src/fetch/payouts.py
index 1effdfa3..f538a23d 100644
--- a/src/fetch/payouts.py
+++ b/src/fetch/payouts.py
@@ -136,11 +136,19 @@ def total_outgoing_eth(self) -> int:
 
     def total_cow_reward(self) -> int:
         """Total outgoing COW token reward"""
-        return int(self.reward_scaling() * self.primary_reward_cow)
+        return (
+            int(self.reward_scaling() * self.primary_reward_cow)
+            if self.primary_reward_cow > 0
+            else self.primary_reward_cow
+        )
 
     def total_eth_reward(self) -> int:
         """Total outgoing ETH reward"""
-        return int(self.reward_scaling() * self.primary_reward_eth)
+        return (
+            int(self.reward_scaling() * self.primary_reward_eth)
+            if self.primary_reward_eth > 0
+            else self.primary_reward_eth
+        )
 
     def reward_scaling(self) -> Fraction:
         """Scaling factor for service fee
@@ -149,7 +157,9 @@ def reward_scaling(self) -> Fraction:
 
     def total_service_fee(self) -> Fraction:
         """Total service fee charged from rewards"""
-        return self.service_fee * (self.primary_reward_cow + self.quote_reward_cow)
+        return self.service_fee * (
+            max(self.primary_reward_cow, 0) + self.quote_reward_cow
+        )
 
     def is_overdraft(self) -> bool:
         """
diff --git a/tests/unit/test_payouts.py b/tests/unit/test_payouts.py
index 05e2c566..96ae5804 100644
--- a/tests/unit/test_payouts.py
+++ b/tests/unit/test_payouts.py
@@ -605,6 +605,17 @@ def test_performance_reward_service_fee(self):
             num_quotes=num_quotes,
             service_fee=service_fee,
         )
+
+        self.assertTrue(
+            test_datum.total_cow_reward(),
+            test_datum.total_eth_reward() * self.conversion_rate,
+        )  # ensure consistency of cow and eth batch rewards
+        self.assertEqual(
+            test_datum.total_service_fee(),
+            int(
+                primary_reward * self.conversion_rate * service_fee
+            ),  # only quote rewards enter
+        )
         self.assertFalse(test_datum.is_overdraft())
         self.assertEqual(
             test_datum.as_payouts(),
@@ -621,26 +632,116 @@ def test_performance_reward_service_fee(self):
     def test_quote_reward_service_fee(self):
         """Sevice fee reduces COW reward."""
         primary_reward, num_quotes, service_fee = 0, 100, Fraction(15, 100)
+        reward_per_quote = 6 * 10**18
+
         test_datum = self.sample_record(
             primary_reward=primary_reward,
             slippage=0,
             num_quotes=num_quotes,
             service_fee=service_fee,
         )
+
+        self.assertEqual(
+            test_datum.total_service_fee(),
+            int(
+                reward_per_quote * num_quotes * service_fee
+            ),  # only quote rewards enter
+        )
+        self.assertFalse(test_datum.is_overdraft())
+        self.assertEqual(
+            test_datum.as_payouts(),
+            [
+                Transfer(
+                    token=self.cow_token,
+                    recipient=self.reward_target,
+                    amount_wei=int(reward_per_quote * num_quotes * (1 - service_fee)),
+                ),
+            ],
+        )
+
+    def test_positive_reward_service_fee(self):
+        """Sevice fee reduces COW reward."""
+        primary_reward = 10**18  # positive reward
+        num_quotes = 100
+        service_fee = Fraction(15, 100)
+        reward_per_quote = 6 * 10**18
+
+        test_datum = self.sample_record(
+            primary_reward=primary_reward,
+            slippage=0,
+            num_quotes=num_quotes,
+            service_fee=service_fee,
+        )
+
+        self.assertEqual(
+            test_datum.total_service_fee(),
+            int(
+                (primary_reward * self.conversion_rate + reward_per_quote * num_quotes)
+                * service_fee
+            ),
+        )
         self.assertFalse(test_datum.is_overdraft())
         self.assertEqual(
             test_datum.as_payouts(),
             [
+                Transfer(
+                    token=self.cow_token,
+                    recipient=self.reward_target,
+                    amount_wei=int(reward_per_quote * num_quotes * (1 - service_fee)),
+                ),
                 Transfer(
                     token=self.cow_token,
                     recipient=self.reward_target,
                     amount_wei=int(
-                        6000000000000000000 * num_quotes * (1 - service_fee)
+                        primary_reward * self.conversion_rate * (1 - service_fee)
                     ),
                 ),
             ],
         )
 
+    def test_negative_reward_service_fee(self):
+        """Sevice fee reduces COW quote reward but not reduce a negative batch reward."""
+        primary_reward = -(10**18)  # negative reward
+        slippage = 2 * 10**18  # to avoid overdraft
+        num_quotes = 100
+        service_fee = Fraction(15, 100)
+        reward_per_quote = 6 * 10**18
+
+        test_datum = self.sample_record(
+            primary_reward=primary_reward,
+            slippage=slippage,
+            num_quotes=num_quotes,
+            service_fee=service_fee,
+        )
+
+        self.assertTrue(
+            test_datum.total_cow_reward(),
+            test_datum.total_eth_reward() * self.conversion_rate,
+        )  # ensure consistency of cow and eth batch rewards
+        self.assertEqual(
+            test_datum.total_service_fee(),
+            int(
+                reward_per_quote * num_quotes * service_fee
+            ),  # only quote rewards enter
+        )
+        self.assertFalse(test_datum.is_overdraft())
+        self.assertEqual(
+            test_datum.as_payouts(),
+            [
+                Transfer(
+                    token=self.cow_token,
+                    recipient=self.reward_target,
+                    amount_wei=int(reward_per_quote * num_quotes * (1 - service_fee)),
+                ),
+                Transfer(
+                    token=None,
+                    recipient=self.buffer_accounting_target,
+                    amount_wei=slippage
+                    + primary_reward,  # no multiplication by 1 - service_fee
+                ),
+            ],
+        )
+
 
 if __name__ == "__main__":
     unittest.main()