diff --git a/rslib/src/tags/bulkadd.rs b/rslib/src/tags/bulkadd.rs
new file mode 100644
index 000000000..dcb9c5f03
--- /dev/null
+++ b/rslib/src/tags/bulkadd.rs
@@ -0,0 +1,88 @@
+// Copyright: Ankitects Pty Ltd and contributors
+// License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
+
+//! Adding tags to selected notes in the browse screen.
+
+use std::collections::HashSet;
+use unicase::UniCase;
+
+use super::{join_tags, split_tags};
+use crate::{notes::NoteTags, prelude::*};
+
+impl Collection {
+    pub fn add_tags_to_notes(&mut self, nids: &[NoteID], tags: &str) -> Result<OpOutput<usize>> {
+        self.transact(Op::UpdateTag, |col| col.add_tags_to_notes_inner(nids, tags))
+    }
+}
+
+impl Collection {
+    fn add_tags_to_notes_inner(&mut self, nids: &[NoteID], tags: &str) -> Result<usize> {
+        let usn = self.usn()?;
+
+        // will update tag list for any new tags, and match case
+        let tags_to_add = self.canonified_tags_as_vec(tags, usn)?;
+
+        // modify notes
+        let mut match_count = 0;
+        let notes = self.storage.get_note_tags_by_id_list(nids)?;
+        for original in notes {
+            if let Some(updated_tags) = add_missing_tags(&original.tags, &tags_to_add) {
+                match_count += 1;
+                let mut note = NoteTags {
+                    tags: updated_tags,
+                    ..original
+                };
+                note.set_modified(usn);
+                self.update_note_tags_undoable(&note, original)?;
+            }
+        }
+
+        Ok(match_count)
+    }
+}
+
+/// Returns the sorted new tag string if any tags were added.
+fn add_missing_tags(note_tags: &str, desired: &[UniCase<String>]) -> Option<String> {
+    let mut note_tags: HashSet<_> = split_tags(note_tags)
+        .map(ToOwned::to_owned)
+        .map(UniCase::new)
+        .collect();
+
+    let mut modified = false;
+    for tag in desired {
+        if !note_tags.contains(tag) {
+            note_tags.insert(tag.clone());
+            modified = true;
+        }
+    }
+    if !modified {
+        return None;
+    }
+
+    // sort
+    let mut tags: Vec<_> = note_tags.into_iter().collect::<Vec<_>>();
+    tags.sort_unstable();
+
+    // turn back into a string
+    let tags: Vec<_> = tags.into_iter().map(|s| s.into_inner()).collect();
+    Some(join_tags(&tags))
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn add_missing() {
+        let desired: Vec<_> = ["xyz", "abc", "DEF"]
+            .iter()
+            .map(|s| UniCase::new(s.to_string()))
+            .collect();
+
+        let add_to = |text| add_missing_tags(text, &desired).unwrap();
+
+        assert_eq!(&add_to(""), " abc DEF xyz ");
+        assert_eq!(&add_to("XYZ deF aaa"), " aaa abc deF XYZ ");
+        assert_eq!(add_missing_tags("def xyz abc", &desired).is_none(), true);
+    }
+}
diff --git a/rslib/src/tags/mod.rs b/rslib/src/tags/mod.rs
index e243840f3..289d97525 100644
--- a/rslib/src/tags/mod.rs
+++ b/rslib/src/tags/mod.rs
@@ -1,6 +1,7 @@
 // Copyright: Ankitects Pty Ltd and contributors
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
+mod bulkadd;
 mod dragdrop;
 mod prefix_replacer;
 mod register;
diff --git a/rslib/src/tags/register.rs b/rslib/src/tags/register.rs
index d7c2b356b..7be6f475b 100644
--- a/rslib/src/tags/register.rs
+++ b/rslib/src/tags/register.rs
@@ -38,6 +38,23 @@ impl Collection {
         Ok((tags, added))
     }
 
+    /// Returns true if any cards were added to the tag list.
+    pub(crate) fn canonified_tags_as_vec(
+        &mut self,
+        tags: &str,
+        usn: Usn,
+    ) -> Result<Vec<UniCase<String>>> {
+        let mut out_tags = vec![];
+
+        for tag in split_tags(tags) {
+            let mut tag = Tag::new(tag.to_string(), usn);
+            self.register_tag(&mut tag)?;
+            out_tags.push(UniCase::new(tag.name));
+        }
+
+        Ok(out_tags)
+    }
+
     /// Adjust tag casing to match any existing parents, and register it if it's not already
     /// in the tags list. True if the tag was added and not already in tag list.
     /// In the case the tag is already registered, tag will be mutated to match the existing
diff --git a/rslib/src/tags/selectednotes.rs b/rslib/src/tags/selectednotes.rs
index 31bf42cde..cc0008458 100644
--- a/rslib/src/tags/selectednotes.rs
+++ b/rslib/src/tags/selectednotes.rs
@@ -57,42 +57,6 @@ impl Collection {
             self.replace_tags_for_notes_inner(nids, &tags, repl)
         }
     }
-
-    pub fn add_tags_to_notes(&mut self, nids: &[NoteID], tags: &str) -> Result<OpOutput<usize>> {
-        let tags: Vec<_> = split_tags(tags).collect();
-        let matcher = regex::RegexSet::new(
-            tags.iter()
-                .map(|s| regex::escape(s))
-                .map(|s| format!("(?i)^{}$", s)),
-        )
-        .map_err(|_| AnkiError::invalid_input("invalid regex"))?;
-
-        self.transact(Op::UpdateTag, |col| {
-            col.transform_notes(nids, |note, _nt| {
-                let mut need_to_add = true;
-                let mut match_count = 0;
-                for tag in &note.tags {
-                    if matcher.is_match(tag) {
-                        match_count += 1;
-                    }
-                    if match_count == tags.len() {
-                        need_to_add = false;
-                        break;
-                    }
-                }
-
-                if need_to_add {
-                    note.tags.extend(tags.iter().map(|&s| s.to_string()))
-                }
-
-                Ok(TransformNoteOutput {
-                    changed: need_to_add,
-                    generate_cards: false,
-                    mark_modified: true,
-                })
-            })
-        })
-    }
 }
 
 #[cfg(test)]