diff --git a/Elwig/Helpers/Billing/Billing.cs b/Elwig/Helpers/Billing/Billing.cs
index 545367b..ff97ac7 100644
--- a/Elwig/Helpers/Billing/Billing.cs
+++ b/Elwig/Helpers/Billing/Billing.cs
@@ -181,19 +181,30 @@ namespace Elwig.Helpers.Billing {
                     }
                 }
 
-                var changes = new List<(int, int, int, int)>();
+                var negChanges = new List<(int, int, int, int)>();
+                var posChanges = new List<(int, int, int, int)>();
                 foreach (var (did, dpnr, _, w) in fittingDeliveries) {
                     int v = Math.Min(needed, w);
                     needed -= v;
-                    changes.Add((did, dpnr, 1, v));
-                    changes.Add((did, dpnr, 2, w - v));
+                    posChanges.Add((did, dpnr, 1, v));
+                    negChanges.Add((did, dpnr, 2, w - v));
                     if (needed == 0) break;
                 }
 
                 using (var cmd = cnx.CreateCommand()) {
                     cmd.CommandText = $"""
                         INSERT INTO delivery_part_bin (year, did, dpnr, binnr, discr, value)
-                        VALUES {string.Join(",\n       ", changes.Select(i => $"({Year}, {i.Item1}, {i.Item2}, {i.Item3}, '', {i.Item4})"))}
+                        VALUES {string.Join(",\n       ", posChanges.Select(i => $"({Year}, {i.Item1}, {i.Item2}, {i.Item3}, '', {i.Item4})"))}
+                        ON CONFLICT DO UPDATE
+                        SET value = value + excluded.value
+                        """;
+                    await cmd.ExecuteNonQueryAsync();
+                }
+
+                using (var cmd = cnx.CreateCommand()) {
+                    cmd.CommandText = $"""
+                        INSERT INTO delivery_part_bin (year, did, dpnr, binnr, discr, value)
+                        VALUES {string.Join(",\n       ", negChanges.Select(i => $"({Year}, {i.Item1}, {i.Item2}, {i.Item3}, '', {i.Item4})"))}
                         ON CONFLICT DO UPDATE
                         SET value = excluded.value
                         """;