diff --git a/internal/cli/format.go b/internal/cli/format.go
index ffaa03a..5842178 100644
--- a/internal/cli/format.go
+++ b/internal/cli/format.go
@@ -40,6 +40,8 @@ func (f *Format) Run() error {
 		return fmt.Errorf("%w: failed to read config file", err)
 	}
 
+	globalExcludes, err := format.CompileGlobs(cfg.Global.Excludes)
+
 	// create optional formatter filter set
 	formatterSet := make(map[string]bool)
 	for _, name := range Cli.Formatters {
@@ -68,7 +70,7 @@ func (f *Format) Run() error {
 			continue
 		}
 
-		err = formatter.Init(name)
+		err = formatter.Init(name, globalExcludes)
 		if err == format.ErrFormatterNotFound && Cli.AllowMissingFormatter {
 			l.Debugf("formatter not found: %v", name)
 			// remove this formatter
diff --git a/internal/cli/format_test.go b/internal/cli/format_test.go
index 088ece6..3aa319a 100644
--- a/internal/cli/format_test.go
+++ b/internal/cli/format_test.go
@@ -2,104 +2,21 @@ package cli
 
 import (
 	"fmt"
-	"io"
-	"os"
-	"path/filepath"
 	"testing"
 
+	"git.numtide.com/numtide/treefmt/internal/test"
+
 	"git.numtide.com/numtide/treefmt/internal/format"
-	"github.com/BurntSushi/toml"
-	"github.com/alecthomas/kong"
-	cp "github.com/otiai10/copy"
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
-func writeConfig(t *testing.T, path string, cfg format.Config) {
-	t.Helper()
-	f, err := os.Create(path)
-	if err != nil {
-		t.Fatalf("failed to create a new config file: %v", err)
-	}
-	encoder := toml.NewEncoder(f)
-	if err = encoder.Encode(cfg); err != nil {
-		t.Fatalf("failed to write to config file: %v", err)
-	}
-}
-
-func newKong(t *testing.T, cli interface{}, options ...kong.Option) *kong.Kong {
-	t.Helper()
-	options = append([]kong.Option{
-		kong.Name("test"),
-		kong.Exit(func(int) {
-			t.Helper()
-			t.Fatalf("unexpected exit()")
-		}),
-	}, options...)
-	parser, err := kong.New(cli, options...)
-	assert.NoError(t, err)
-	return parser
-}
-
-func tempFile(t *testing.T, path string) *os.File {
-	t.Helper()
-	file, err := os.Create(path)
-	if err != nil {
-		t.Fatalf("failed to create temporary file: %v", err)
-	}
-	return file
-}
-
-func cmd(t *testing.T, args ...string) ([]byte, error) {
-	t.Helper()
-
-	// create a new kong context
-	p := newKong(t, &Cli)
-	ctx, err := p.Parse(args)
-	if err != nil {
-		return nil, err
-	}
-
-	tempDir := t.TempDir()
-	tempOut := tempFile(t, filepath.Join(tempDir, "combined_output"))
-
-	// capture standard outputs before swapping them
-	stdout := os.Stdout
-	stderr := os.Stderr
-
-	// swap them temporarily
-	os.Stdout = tempOut
-	os.Stderr = tempOut
-
-	// run the command
-	if err = ctx.Run(); err != nil {
-		return nil, err
-	}
-
-	// reset and read the temporary output
-	if _, err = tempOut.Seek(0, 0); err != nil {
-		return nil, fmt.Errorf("%w: failed to reset temp output for reading", err)
-	}
-
-	out, err := io.ReadAll(tempOut)
-	if err != nil {
-		return nil, fmt.Errorf("%w: failed to read temp output", err)
-	}
-
-	// swap outputs back
-	os.Stdout = stdout
-	os.Stderr = stderr
-
-	return out, nil
-}
-
 func TestAllowMissingFormatter(t *testing.T) {
 	as := require.New(t)
 
 	tempDir := t.TempDir()
 	configPath := tempDir + "/treefmt.toml"
 
-	writeConfig(t, configPath, format.Config{
+	test.WriteConfig(t, configPath, format.Config{
 		Formatters: map[string]*format.Formatter{
 			"foo-fmt": {
 				Command: "foo-fmt",
@@ -117,12 +34,10 @@ func TestAllowMissingFormatter(t *testing.T) {
 func TestSpecifyingFormatters(t *testing.T) {
 	as := require.New(t)
 
-	tempDir := t.TempDir()
+	tempDir := test.TempExamples(t)
 	configPath := tempDir + "/treefmt.toml"
 
-	as.NoError(cp.Copy("../../test/examples", tempDir), "failed to copy test data to temp dir")
-
-	writeConfig(t, configPath, format.Config{
+	test.WriteConfig(t, configPath, format.Config{
 		Formatters: map[string]*format.Formatter{
 			"elm": {
 				Command:  "echo",
@@ -163,3 +78,75 @@ func TestSpecifyingFormatters(t *testing.T) {
 	out, err = cmd(t, "--clear-cache", "--config-file", configPath, "--tree-root", tempDir, "--formatters", "bar,foo")
 	as.Errorf(err, "formatter not found in config: bar")
 }
+
+func TestIncludesAndExcludes(t *testing.T) {
+	as := require.New(t)
+
+	tempDir := test.TempExamples(t)
+	configPath := tempDir + "/echo.toml"
+
+	// test without any excludes
+	config := format.Config{
+		Formatters: map[string]*format.Formatter{
+			"echo": {
+				Command:  "echo",
+				Includes: []string{"*"},
+			},
+		},
+	}
+
+	test.WriteConfig(t, configPath, config)
+	out, err := cmd(t, "-c", "--config-file", configPath, "--tree-root", tempDir)
+	as.NoError(err)
+	as.Contains(string(out), fmt.Sprintf("%d files changed", 29))
+
+	// globally exclude nix files
+	config.Global = struct{ Excludes []string }{
+		Excludes: []string{"*.nix"},
+	}
+
+	test.WriteConfig(t, configPath, config)
+	out, err = cmd(t, "-c", "--config-file", configPath, "--tree-root", tempDir)
+	as.NoError(err)
+	as.Contains(string(out), fmt.Sprintf("%d files changed", 28))
+
+	// add haskell files to the global exclude
+	config.Global.Excludes = []string{"*.nix", "*.hs"}
+
+	test.WriteConfig(t, configPath, config)
+	out, err = cmd(t, "-c", "--config-file", configPath, "--tree-root", tempDir)
+	as.NoError(err)
+	as.Contains(string(out), fmt.Sprintf("%d files changed", 22))
+
+	// remove python files from the echo formatter
+	config.Formatters["echo"].Excludes = []string{"*.py"}
+
+	test.WriteConfig(t, configPath, config)
+	out, err = cmd(t, "-c", "--config-file", configPath, "--tree-root", tempDir)
+	as.NoError(err)
+	as.Contains(string(out), fmt.Sprintf("%d files changed", 20))
+
+	// remove go files from the echo formatter
+	config.Formatters["echo"].Excludes = []string{"*.py", "*.go"}
+
+	test.WriteConfig(t, configPath, config)
+	out, err = cmd(t, "-c", "--config-file", configPath, "--tree-root", tempDir)
+	as.NoError(err)
+	as.Contains(string(out), fmt.Sprintf("%d files changed", 19))
+
+	// adjust the includes for echo to only include elm files
+	config.Formatters["echo"].Includes = []string{"*.elm"}
+
+	test.WriteConfig(t, configPath, config)
+	out, err = cmd(t, "-c", "--config-file", configPath, "--tree-root", tempDir)
+	as.NoError(err)
+	as.Contains(string(out), fmt.Sprintf("%d files changed", 1))
+
+	// add js files to echo formatter
+	config.Formatters["echo"].Includes = []string{"*.elm", "*.js"}
+
+	test.WriteConfig(t, configPath, config)
+	out, err = cmd(t, "-c", "--config-file", configPath, "--tree-root", tempDir)
+	as.NoError(err)
+	as.Contains(string(out), fmt.Sprintf("%d files changed", 2))
+}
diff --git a/internal/cli/helpers_test.go b/internal/cli/helpers_test.go
new file mode 100644
index 0000000..7268d23
--- /dev/null
+++ b/internal/cli/helpers_test.go
@@ -0,0 +1,70 @@
+package cli
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"git.numtide.com/numtide/treefmt/internal/test"
+	"github.com/alecthomas/kong"
+	"github.com/stretchr/testify/require"
+)
+
+func newKong(t *testing.T, cli interface{}, options ...kong.Option) *kong.Kong {
+	t.Helper()
+	options = append([]kong.Option{
+		kong.Name("test"),
+		kong.Exit(func(int) {
+			t.Helper()
+			t.Fatalf("unexpected exit()")
+		}),
+	}, options...)
+	parser, err := kong.New(cli, options...)
+	require.NoError(t, err)
+	return parser
+}
+
+func cmd(t *testing.T, args ...string) ([]byte, error) {
+	t.Helper()
+
+	// create a new kong context
+	p := newKong(t, &Cli)
+	ctx, err := p.Parse(args)
+	if err != nil {
+		return nil, err
+	}
+
+	tempDir := t.TempDir()
+	tempOut := test.TempFile(t, filepath.Join(tempDir, "combined_output"))
+
+	// capture standard outputs before swapping them
+	stdout := os.Stdout
+	stderr := os.Stderr
+
+	// swap them temporarily
+	os.Stdout = tempOut
+	os.Stderr = tempOut
+
+	// run the command
+	if err = ctx.Run(); err != nil {
+		return nil, err
+	}
+
+	// reset and read the temporary output
+	if _, err = tempOut.Seek(0, 0); err != nil {
+		return nil, fmt.Errorf("%w: failed to reset temp output for reading", err)
+	}
+
+	out, err := io.ReadAll(tempOut)
+	if err != nil {
+		return nil, fmt.Errorf("%w: failed to read temp output", err)
+	}
+
+	// swap outputs back
+	os.Stdout = stdout
+	os.Stderr = stderr
+
+	return out, nil
+}
diff --git a/internal/format/config.go b/internal/format/config.go
index 6287da0..29b127d 100644
--- a/internal/format/config.go
+++ b/internal/format/config.go
@@ -4,6 +4,10 @@ import "github.com/BurntSushi/toml"
 
 // Config is used to represent the list of configured Formatters.
 type Config struct {
+	Global struct {
+		// Excludes is an optional list of glob patterns used to exclude certain files from all formatters.
+		Excludes []string
+	}
 	Formatters map[string]*Formatter `toml:"formatter"`
 }
 
diff --git a/internal/format/format.go b/internal/format/format.go
index 4049a18..c1ab066 100644
--- a/internal/format/format.go
+++ b/internal/format/format.go
@@ -48,7 +48,9 @@ func (f *Formatter) Executable() string {
 }
 
 // Init is used to initialise internal state before this Formatter is ready to accept paths.
-func (f *Formatter) Init(name string) error {
+func (f *Formatter) Init(name string, globalExcludes []glob.Glob) error {
+	var err error
+
 	// capture the name from the config file
 	f.name = name
 
@@ -68,26 +70,16 @@ func (f *Formatter) Init(name string) error {
 	f.batch = make([]string, f.batchSize)
 	f.batch = f.batch[:0]
 
-	// todo refactor common code below
-	if len(f.Includes) > 0 {
-		for _, pattern := range f.Includes {
-			g, err := glob.Compile("**/" + pattern)
-			if err != nil {
-				return fmt.Errorf("%w: failed to compile include pattern '%v' for formatter '%v'", err, pattern, f.name)
-			}
-			f.includes = append(f.includes, g)
-		}
+	f.includes, err = CompileGlobs(f.Includes)
+	if err != nil {
+		return fmt.Errorf("%w: formatter '%v' includes", err, f.name)
 	}
 
-	if len(f.Excludes) > 0 {
-		for _, pattern := range f.Excludes {
-			g, err := glob.Compile("**/" + pattern)
-			if err != nil {
-				return fmt.Errorf("%w: failed to compile exclude pattern '%v' for formatter '%v'", err, pattern, f.name)
-			}
-			f.excludes = append(f.excludes, g)
-		}
+	f.excludes, err = CompileGlobs(f.Excludes)
+	if err != nil {
+		return fmt.Errorf("%w: formatter '%v' excludes", err, f.name)
 	}
+	f.excludes = append(f.excludes, globalExcludes...)
 
 	return nil
 }
diff --git a/internal/format/glob.go b/internal/format/glob.go
index e883fb6..947ec9f 100644
--- a/internal/format/glob.go
+++ b/internal/format/glob.go
@@ -1,9 +1,26 @@
 package format
 
 import (
+	"fmt"
+
 	"github.com/gobwas/glob"
 )
 
+// CompileGlobs prepares the globs, where the patterns are all right-matching.
+func CompileGlobs(patterns []string) ([]glob.Glob, error) {
+	globs := make([]glob.Glob, len(patterns))
+
+	for i, pattern := range patterns {
+		g, err := glob.Compile("**/" + pattern)
+		if err != nil {
+			return nil, fmt.Errorf("%w: failed to compile include pattern '%v'", err, pattern)
+		}
+		globs[i] = g
+	}
+
+	return globs, nil
+}
+
 func PathMatches(path string, globs []glob.Glob) bool {
 	for idx := range globs {
 		if globs[idx].Match(path) {
diff --git a/internal/test/temp.go b/internal/test/temp.go
new file mode 100644
index 0000000..c997d80
--- /dev/null
+++ b/internal/test/temp.go
@@ -0,0 +1,38 @@
+package test
+
+import (
+	"os"
+	"testing"
+
+	"git.numtide.com/numtide/treefmt/internal/format"
+	"github.com/BurntSushi/toml"
+	cp "github.com/otiai10/copy"
+	"github.com/stretchr/testify/require"
+)
+
+func WriteConfig(t *testing.T, path string, cfg format.Config) {
+	t.Helper()
+	f, err := os.Create(path)
+	if err != nil {
+		t.Fatalf("failed to create a new config file: %v", err)
+	}
+	encoder := toml.NewEncoder(f)
+	if err = encoder.Encode(cfg); err != nil {
+		t.Fatalf("failed to write to config file: %v", err)
+	}
+}
+
+func TempExamples(t *testing.T) string {
+	tempDir := t.TempDir()
+	require.NoError(t, cp.Copy("../../test/examples", tempDir), "failed to copy test data to temp dir")
+	return tempDir
+}
+
+func TempFile(t *testing.T, path string) *os.File {
+	t.Helper()
+	file, err := os.Create(path)
+	if err != nil {
+		t.Fatalf("failed to create temporary file: %v", err)
+	}
+	return file
+}