diff --git a/tests/test__zk_new.sh b/tests/test__zk_new.sh
new file mode 100644
index 0000000..7197ab9
--- /dev/null
+++ b/tests/test__zk_new.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+TMP_ZETTELKASTEN=""
+
+setup() {
+    source ../zk
+
+    TMP_ZETTELKASTEN="$(mktemp -d)"
+}
+
+teardown() {
+    rm -rf "$TMP_ZETTELKASTEN"
+}
+
+test__zk_new_creates_file_in_correct_directory() {
+    export ZKDIR="$TMP_ZETTELKASTEN"
+    filename="aaaaaaaaaaaaaa"
+    fake date "echo $filename"
+
+    _zk_new
+
+    assert "test -e $TMP_ZETTELKASTEN/$filename"
+}
diff --git a/tests/test_isosec.sh b/tests/test_isosec.sh
new file mode 100644
index 0000000..3a23014
--- /dev/null
+++ b/tests/test_isosec.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+
+setup() {
+    source ../zk
+}
+
+test_isosec_calls_date_with_correct_parameters() {
+    expected="date -u +%Y%m%d%H%M%S"
+    # shellcheck disable=SC2016
+    fake date echo 'date ${FAKE_PARAMS[@]}'
+
+    result="$(_zk_isosec)"
+
+    assert_equals "$expected" "$result"
+}
diff --git a/zk b/zk
index 4efa728..e11c9b9 100755
--- a/zk
+++ b/zk
@@ -14,12 +14,21 @@ get_command() {
 	done
 }
 
+_zk_isosec() {
+	date -u +%Y%m%d%H%M%S
+}
+
 _zk_list() {
 	for zettel in "$ZKDIR"/*; do
 		echo "$(basename "$zettel") | $(head -1 "$zettel")"
 	done
 }
 
+_zk_new() {
+	filename="$(_zk_isosec)"
+	touch "$ZKDIR/$filename"
+}
+
 main() {
 	subcommand="$(get_commands "$COMMANDS" "$1")"
 	_zk_"$subcommand"