diff --git a/libbeat/esleg/eslegclient/bulkapi.go b/libbeat/esleg/eslegclient/bulkapi.go
index c70fad12a14..965215fe310 100644
--- a/libbeat/esleg/eslegclient/bulkapi.go
+++ b/libbeat/esleg/eslegclient/bulkapi.go
@@ -75,8 +75,6 @@ func (conn *Connection) Bulk(
 		return 0, nil, nil
 	}
 
-	mergedParams := mergeParams(conn.ConnectionSettings.Parameters, params)
-
 	enc := conn.Encoder
 	enc.Reset()
 	if err := bulkEncode(conn.log, enc, body); err != nil {
@@ -84,6 +82,8 @@ func (conn *Connection) Bulk(
 		return 0, nil, err
 	}
 
+	mergedParams := mergeParams(conn.ConnectionSettings.Parameters, params)
+
 	requ, err := newBulkRequest(conn.URL, index, docType, mergedParams, enc)
 	if err != nil {
 		apm.CaptureError(ctx, err).Send()
@@ -105,8 +105,6 @@ func (conn *Connection) SendMonitoringBulk(
 		return nil, nil
 	}
 
-	mergedParams := mergeParams(conn.ConnectionSettings.Parameters, params)
-
 	enc := conn.Encoder
 	enc.Reset()
 	if err := bulkEncode(conn.log, enc, body); err != nil {
@@ -119,6 +117,8 @@ func (conn *Connection) SendMonitoringBulk(
 		}
 	}
 
+	mergedParams := mergeParams(conn.ConnectionSettings.Parameters, params)
+
 	requ, err := newMonitoringBulkRequest(conn.GetVersion(), conn.URL, mergedParams, enc)
 	if err != nil {
 		return nil, err
diff --git a/libbeat/esleg/eslegclient/bulkapi_mock_test.go b/libbeat/esleg/eslegclient/bulkapi_mock_test.go
index 44430eac614..3d4e33c4271 100644
--- a/libbeat/esleg/eslegclient/bulkapi_mock_test.go
+++ b/libbeat/esleg/eslegclient/bulkapi_mock_test.go
@@ -24,11 +24,13 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
+	"net/url"
 	"os"
 	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/elastic/beats/v7/libbeat/logp"
 )
@@ -151,21 +153,7 @@ func TestOneHost503Resp_Bulk(t *testing.T) {
 }
 
 func TestEnforceParameters(t *testing.T) {
-	client, _ := NewConnection(ConnectionSettings{
-		Parameters: map[string]string{"hello": "world"},
-		URL:        "http://localhost",
-		Timeout:    0,
-	})
-	client.Encoder = NewJSONEncoder(nil, false)
-
-	client.HTTP = &reqInspector{
-		assert: func(req *http.Request) (*http.Response, error) {
-			assert.Equal(t, "world", req.URL.Query().Get("hello"))
-			// short circuit others logic.
-			return nil, errors.New("shortcut")
-		},
-	}
-
+	// Prepare the test bulk request.
 	index := "what"
 
 	ops := []map[string]interface{}{
@@ -186,11 +174,84 @@ func TestEnforceParameters(t *testing.T) {
 		body = append(body, op)
 	}
 
-	params := map[string]string{
-		"refresh": "true",
+	tests := map[string]struct {
+		preconfigured map[string]string
+		reqParams     map[string]string
+		expected      map[string]string
+	}{
+		"Preconfigured parameters are applied to bulk requests": {
+			preconfigured: map[string]string{
+				"hello": "world",
+			},
+			expected: map[string]string{
+				"hello": "world",
+			},
+		},
+		"Preconfigured and local parameters are merged": {
+			preconfigured: map[string]string{
+				"hello": "world",
+			},
+			reqParams: map[string]string{
+				"foo": "bar",
+			},
+			expected: map[string]string{
+				"hello": "world",
+				"foo":   "bar",
+			},
+		},
+		"Local parameters only": {
+			reqParams: map[string]string{
+				"foo": "bar",
+			},
+			expected: map[string]string{
+				"foo": "bar",
+			},
+		},
+		"no parameters": {
+			expected: map[string]string{},
+		},
+		"Local overrides preconfigured parameters": {
+			preconfigured: map[string]string{
+				"foo": "world",
+			},
+			reqParams: map[string]string{
+				"foo": "bar",
+			},
+			expected: map[string]string{
+				"foo": "bar",
+			},
+		},
 	}
 
-	client.Bulk(context.Background(), index, "type1", params, body)
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			client, _ := NewConnection(ConnectionSettings{
+				Parameters: test.preconfigured,
+				URL:        "http://localhost",
+				Timeout:    0,
+			})
+
+			client.Encoder = NewJSONEncoder(nil, false)
+
+			var recParams url.Values
+			errShort := errors.New("shortcut")
+
+			client.HTTP = &reqInspector{
+				assert: func(req *http.Request) (*http.Response, error) {
+					recParams = req.URL.Query()
+					return nil, errShort
+				},
+			}
+
+			_, _, err := client.Bulk(context.Background(), index, "type1", test.reqParams, body)
+			require.Equal(t, errShort, err)
+			require.Equal(t, len(recParams), len(test.expected))
+
+			for k, v := range test.expected {
+				assert.Equal(t, recParams.Get(k), v)
+			}
+		})
+	}
 }
 
 type reqInspector struct {