diff --git a/backend/mpc-system/services/account/adapters/input/http/account_handler.go b/backend/mpc-system/services/account/adapters/input/http/account_handler.go
index 3e577bd3..b8409344 100644
--- a/backend/mpc-system/services/account/adapters/input/http/account_handler.go
+++ b/backend/mpc-system/services/account/adapters/input/http/account_handler.go
@@ -732,12 +732,26 @@ func (h *AccountHTTPHandler) CreateSigningSession(c *gin.Context) {
 			zap.String("username", req.Username),
 			zap.Strings("configured_parties", partyIDs))
 	} else {
-		// Use all active parties (original behavior)
-		partyIDs = allActivePartyIDs
+		// For threshold signing, select minimum required parties (threshold_t)
+		// For 2-of-3, we need exactly 2 parties to sign (not all 3)
+		requiredParties := accountOutput.Account.ThresholdT
+		if len(allActivePartyIDs) < requiredParties {
+			c.JSON(http.StatusBadRequest, gin.H{
+				"error":            "insufficient active parties for signing",
+				"required":         requiredParties,
+				"available":        len(allActivePartyIDs),
+			})
+			return
+		}
 
-		logger.Info("Using all active parties for signing",
+		// Select first 'threshold_t' parties
+		partyIDs = allActivePartyIDs[:requiredParties]
+
+		logger.Info("Using minimum required parties for threshold signing",
 			zap.String("username", req.Username),
-			zap.Strings("active_parties", partyIDs))
+			zap.Int("threshold_t", requiredParties),
+			zap.Int("total_active", len(allActivePartyIDs)),
+			zap.Strings("selected_parties", partyIDs))
 	}
 
 	// Check if any of the selected parties is a delegate