diff --git a/src/worker/director.rs b/src/worker/director.rs
index dd4fc51..9ce2e06 100644
--- a/src/worker/director.rs
+++ b/src/worker/director.rs
@@ -808,18 +808,29 @@ impl DirectorWorker {
 
     // compute piece price and full sell price
     let piece_price = Self::compute_piece_sell_price(item);
-    let sell_price = piece_price * item.quantity as f64;
-
+    
         let one_piece_cost = Self::resolve_one_piece_cost(conn, item.product_id, item.sell_cost)?;
         let cumulative_tax_percent = Self::get_cumulative_tax_percent(conn, item.branch_id, item.user_id)?;
 
-        let revenue_cents = (sell_price * 100.0).round() as i64;
-        let cost_cents = (one_piece_cost * item.quantity as f64 * 100.0).round() as i64;
-        let profit_cents = (revenue_cents - cost_cents).max(0);
-        let tax_cents = ((profit_cents as f64) * cumulative_tax_percent / 100.0).round() as i64;
+        // Preis-Inflation: Der Preis wird basierend auf der Steuer inflatiert,
+        // damit der Netto-Betrag für den Verkäufer gleich bleibt (wie im Frontend)
+        let inflation_factor = if cumulative_tax_percent >= 100.0 {
+            1.0
+        } else {
+            1.0 / (1.0 - cumulative_tax_percent / 100.0)
+        };
+        let adjusted_price_per_unit = (piece_price * inflation_factor * 100.0).round() / 100.0;
+        let revenue = adjusted_price_per_unit * item.quantity as f64;
+        
+        // Steuer wird auf Revenue berechnet (nicht auf Profit), wie im Frontend
+        let revenue_cents = (revenue * 100.0).round() as i64;
+        let tax_cents = ((revenue * cumulative_tax_percent / 100.0) * 100.0).round() as i64;
         let payout_cents = revenue_cents - tax_cents;
+        
+        let cost = one_piece_cost * item.quantity as f64;
+        let profit_cents = revenue_cents - (cost * 100.0).round() as i64;
 
-        eprintln!("[DirectorWorker] sell: revenue={:.2}, cost={:.2}, profit_cents={}, tax%={:.2}, tax_cents={}, payout_cents={}", sell_price, one_piece_cost * item.quantity as f64, profit_cents, cumulative_tax_percent, tax_cents, payout_cents);
+        eprintln!("[DirectorWorker] sell: revenue={:.2}, cost={:.2}, profit_cents={}, tax%={:.2}, tax_cents={}, payout_cents={}", revenue, cost, profit_cents, cumulative_tax_percent, tax_cents, payout_cents);
 
         if tax_cents > 0 {
             let tax_amount = (tax_cents as f64) / 100.0;
@@ -837,7 +848,7 @@ impl DirectorWorker {
         eprintln!(
             "[DirectorWorker] sell: user_id={}, revenue={:.2}, tax={:.2}, payout={:.2}, product_id={}",
             item.user_id,
-            sell_price,
+            revenue,
             (tax_cents as f64) / 100.0,
             payout_amount,
             item.product_id
diff --git a/src/worker/sql.rs b/src/worker/sql.rs
index cd325a7..7754ba2 100644
--- a/src/worker/sql.rs
+++ b/src/worker/sql.rs
@@ -208,7 +208,7 @@ DELETE FROM falukant_data.inventory WHERE id = $1;
 pub const QUERY_ADD_SELL_LOG: &str = r#"
 INSERT INTO falukant_log.sell (region_id, product_id, quantity, seller_id, sell_timestamp) 
 VALUES ($1, $2, $3, $4, NOW())
-ON CONFLICT (region_id, product_id, seller_id) 
+ON CONFLICT (seller_id, product_id, region_id) 
 DO UPDATE SET 
     quantity = falukant_log.sell.quantity + EXCLUDED.quantity, 
     sell_timestamp = COALESCE(EXCLUDED.sell_timestamp, NOW());