diff --git a/ledger/file.go b/ledger/file.go
index cdc3d99..4e150f9 100644
--- a/ledger/file.go
+++ b/ledger/file.go
@@ -1,6 +1,12 @@
 package ledger
 
-import "io"
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+var filesAppendDelim = "\t"
 
 type Files []string
 
@@ -11,7 +17,42 @@ func NewFiles(p string, q ...string) (Files, error) {
 }
 
 func (files Files) Add(payee string, delta Delta) error {
-	//   TODO
+	currencyValue := fmt.Sprintf("%s%.2f", delta.Currency, delta.Value)
+	if delta.Currency != USD {
+		currencyValue = fmt.Sprintf("%.2f %s", delta.Value, delta.Currency)
+	}
+	return files.append(fmt.Sprintf("%s   %s\n%s%s%s%s\n%s%s",
+		delta.Date, delta.Description,
+		filesAppendDelim, delta.Name, filesAppendDelim+filesAppendDelim+filesAppendDelim, currencyValue,
+		filesAppendDelim, payee,
+	))
+}
+
+func (files Files) append(s string) error {
+	if err := files.trimTrainlingWhitespace(); err != nil {
+		return err
+	}
+
+	f, err := os.OpenFile(string(files[0]), os.O_APPEND|os.O_CREATE|os.O_WRONLY, os.ModePerm)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	fmt.Fprintf(f, "\n%s", s)
+	return f.Close()
+}
+
+func (files Files) trimTrainlingWhitespace() error {
+	f, err := os.Open(string(files[0]))
+	if os.IsNotExist(err) {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
 	return io.EOF
 }
 
diff --git a/ledger/file_test.go b/ledger/file_test.go
index f32f797..c9eebd1 100644
--- a/ledger/file_test.go
+++ b/ledger/file_test.go
@@ -8,6 +8,7 @@ import (
 )
 
 func TestFileAdd(t *testing.T) {
+	filesAppendDelim = " "
 	payee := "name:3"
 	delta := Delta{
 		Date:        "2999-88-77",
@@ -22,15 +23,17 @@ func TestFileAdd(t *testing.T) {
 	}{
 		"no file": {
 			given: nil,
-			want: `2999-88-77 66
-  name:1 $2.00
-  name:3`,
+			want: `
+2999-88-77   66
+ name:1   $2.00
+ name:3`,
 		},
 		"empty file": {
 			given: []byte{},
-			want: `2999-88-77 66
-  name:1 $2.00
-  name:3`,
+			want: `
+2999-88-77   66
+ name:1   $2.00
+ name:3`,
 		},
 		"happy without trailing whitespace": {
 			given: []byte(`
@@ -41,9 +44,9 @@ func TestFileAdd(t *testing.T) {
 2000-01-02 desc
   name:1 $1.00
   name:2 $-1.00
-2999-88-77 66
-  name:1 $2.00
-  name:3`,
+2999-88-77   66
+ name:1   $2.00
+ name:3`,
 		},
 		"happy with trailing newline": {
 			given: []byte(`
@@ -55,9 +58,9 @@ func TestFileAdd(t *testing.T) {
 2000-01-02 desc
   name:1 $1.00
   name:2 $-1.00
-2999-88-77 66
-  name:1 $2.00
-  name:3`,
+2999-88-77   66
+ name:1   $2.00
+ name:3`,
 		},
 	}