diff --git a/handlers/transaction.go b/handlers/transaction.go
index 9b313d6..ccc77b6 100644
--- a/handlers/transaction.go
+++ b/handlers/transaction.go
@@ -7,7 +7,9 @@ import (
 	"git.agecem.com/agecem/bottin-agenda/data"
 	"git.agecem.com/agecem/bottin-agenda/models"
 	"git.agecem.com/agecem/bottin-agenda/responses"
+	bottindata "git.agecem.com/agecem/bottin/v5/data"
 	"github.com/labstack/echo/v4"
+	"github.com/spf13/viper"
 )
 
 // GetTransactions lists transactions on GET /v2/transactions http/1.1
@@ -73,6 +75,44 @@ func PostTransactions(c echo.Context) error {
 		return c.JSON(statusCode, response)
 	}
 
+	bottinApiKey := viper.GetString("bottin.api.key")
+	bottinApiHost := viper.GetString("bottin.api.host")
+	bottinApiProtocol := viper.GetString("bottin.api.protocol")
+	bottinApiPort := viper.GetInt("bottin.api.port")
+
+	// Using bottin's API client
+	bottinApiClient := bottindata.NewApiClient(
+		bottinApiKey,
+		bottinApiHost,
+		bottinApiProtocol,
+		bottinApiPort,
+	)
+
+	// Check if membre_id exists according to bottin
+	for _, transaction := range transactions {
+		if transaction.MembreID == "" {
+			response.Message = fmt.Sprintf("Cannot insert transaction without a membre_id")
+			statusCode = http.StatusBadRequest
+
+			return c.JSON(statusCode, response)
+		}
+		membre, err := bottinApiClient.GetMembre(transaction.MembreID)
+		if err != nil {
+			response.Message = fmt.Sprintf("Error during bottinApiClient.GetMembre(): %s", err)
+
+			return c.JSON(statusCode, response)
+		}
+
+		if membre.ID == "" {
+			response.Message = fmt.Sprintf("Cannot insert transaction for non-existent membre %s", membre.ID)
+			statusCode = http.StatusNotFound
+
+			return c.JSON(statusCode, response)
+		}
+
+		// membre exists, can keep going
+	}
+
 	// Check for already-existing transactions
 	for _, transaction := range transactions {
 		transaction, err := client.GetTransaction(transaction.MembreID, transaction.IsPerpetual)