diff --git a/cnjvalidator/cnjvalidator.go b/cnjvalidator/cnjvalidator.go
index a4f2e58..668c3c1 100644
--- a/cnjvalidator/cnjvalidator.go
+++ b/cnjvalidator/cnjvalidator.go
@@ -1,6 +1,15 @@
 package cnjvalidator
 
-import "github.com/go-playground/validator/v10"
+import (
+	"errors"
+	"strings"
+
+	gocnjhelper "git.clickandjoin.umbach.dev/ClickandJoin/go-cnj-helper"
+	"github.com/go-playground/validator/v10"
+	"github.com/gocql/gocql"
+	"github.com/gofiber/fiber/v2"
+	"github.com/scylladb/gocqlx/v2"
+)
 
 type ErrorResponse struct {
 	FailedField string
@@ -24,3 +33,61 @@ func ValidateStruct(event interface{}) []*ErrorResponse {
 	}
 	return errors
 }
+
+func HandleAccountNameValidation(scyllaDbSession gocqlx.Session, scyllaDbClusterKeyspace string, accountName string) (int, error) {
+	accountNameLc := strings.ToLower(accountName)
+
+	isAccountNameInUse, err := isValueAlreadyInUse(scyllaDbSession, scyllaDbClusterKeyspace, "account_name_lc", accountNameLc)
+
+	if err != nil {
+		gocnjhelper.LogErrorf("Error account name validation %s", err)
+		return fiber.StatusInternalServerError, err
+	}
+
+	isByLastAccountNameInUse, err := isValueAlreadyInUse(scyllaDbSession, scyllaDbClusterKeyspace, "last_account_name_lc", accountNameLc)
+
+	if err != nil {
+		gocnjhelper.LogErrorf("Error account name validation %s", err)
+		return fiber.StatusInternalServerError, err
+	}
+
+	if isAccountNameInUse || isByLastAccountNameInUse {
+		gocnjhelper.LogDebug("AccountName already in use")
+		return fiber.StatusUnprocessableEntity, errors.New("AccountName already in use")
+	}
+
+	return fiber.StatusOK, nil
+}
+
+func HandleEmailValidation(scyllaDbSession gocqlx.Session, scyllaDbClusterKeyspace string, email string) (int, error) {
+	isEmailInUse, err := isValueAlreadyInUse(scyllaDbSession, scyllaDbClusterKeyspace, "email", email)
+
+	if err != nil {
+		gocnjhelper.LogErrorf("Error email validation %s", err)
+		return fiber.StatusInternalServerError, err
+	}
+
+	if isEmailInUse {
+		gocnjhelper.LogDebug("Email already in use")
+		return fiber.StatusUnprocessableEntity, errors.New("email already in use")
+	}
+
+	return fiber.StatusOK, nil
+}
+
+func isValueAlreadyInUse(scyllaDbSession gocqlx.Session, scyllaDbClusterKeyspace string, table_value string, value string) (alreadyInUse bool, err error) {
+	var foundValue string
+
+	dbErr := scyllaDbSession.Query("SELECT "+table_value+" FROM "+scyllaDbClusterKeyspace+".users WHERE "+table_value+" = '"+value+"'", nil).Get(&foundValue)
+
+	if dbErr != nil && !errors.Is(dbErr, gocql.ErrNotFound) {
+		gocnjhelper.LogErrorf("Failed to check for table: %s, value: %s, err: %s", table_value, value, dbErr)
+		return true, dbErr
+	}
+
+	if foundValue != "" {
+		return true, nil
+	}
+
+	return false, nil
+}