diff --git a/.gitignore b/.gitignore
index 9887811..55f91a1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 vendor
 c.out
+.env
diff --git a/go.mod b/go.mod
index be2ce61..5d204ad 100644
--- a/go.mod
+++ b/go.mod
@@ -3,3 +3,5 @@ module github.com/teamwork/vat/v3
 go 1.21
 
 require github.com/golang/mock v1.6.0
+
+require github.com/joho/godotenv v1.5.1 // indirect
diff --git a/go.sum b/go.sum
index d067127..79eaa87 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,7 @@
 github.com/golang/mock v1.6.0 h1:ErTB+efbowRARo13NNdxyJji2egdxLGQhRaY+DUumQc=
 github.com/golang/mock v1.6.0/go.mod h1:p6yTPP+5HYm5mzsMV8JkE6ZKdX+/wYM6Hr+LicevLPs=
+github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
diff --git a/uk_vat_service_test.go b/uk_vat_service_test.go
index de6d5fa..13a4ae5 100644
--- a/uk_vat_service_test.go
+++ b/uk_vat_service_test.go
@@ -5,8 +5,11 @@ package vat
 
 import (
 	"errors"
+	"os"
 	"testing"
 	"time"
+
+	"github.com/joho/godotenv"
 )
 
 // test numbers to use with the UK VAT service API in their sandbox environment:
@@ -25,11 +28,21 @@ var ukTests = []struct {
 // TestUKVATService tests the UK VAT service. Just meant to be a quick way to check that this service is working.
 // Makes external calls that sometimes might fail. Do not include them in CI/CD.
 func TestUKVATService(t *testing.T) {
+	// Load environment variables from .env file
+	if err := godotenv.Load(); err != nil {
+		t.Fatalf("Error loading .env file: %v", err)
+	}
+
 	opts := ValidatorOpts{
-		UKClientID:     "yourClientID", // insert your own client ID and secret here. Do not commit real values.
-		UKClientSecret: "yourClientSecret",
+		UKClientID:     os.Getenv("CLIENT_ID"),
+		UKClientSecret: os.Getenv("SECRET"),
 		IsUKTest:       true,
 	}
+
+	if opts.UKClientID == "" || opts.UKClientSecret == "" {
+		t.Fatal("CLIENT_ID and SECRET must be set in .env file")
+	}
+
 	token, err := GenerateUKAccessToken(opts)
 	if err != nil {
 		t.Fatal(err)
diff --git a/vies_service_test.go b/vies_service_test.go
index 0468e14..2c343cd 100644
--- a/vies_service_test.go
+++ b/vies_service_test.go
@@ -6,6 +6,7 @@ package vat
 import (
 	"errors"
 	"testing"
+	"time"
 )
 
 var viesTests = []struct {
@@ -26,5 +27,6 @@ func TestViesService(t *testing.T) {
 		if !errors.Is(err, test.expectedError) {
 			t.Errorf("Expected <%v> for %v, got <%v>", test.expectedError, test.vatNumber, err)
 		}
+		time.Sleep(time.Second * 2) // delay to prevent rate limiting
 	}
 }