Does changing a category or tag slug break links?

Name and slug are separate

A term has a Name, shown to readers, and a Slug, used in the URL. On Posts → Categories, editing the name alone changes headings, menus and breadcrumbs and leaves the address untouched. "Coffee Gear" can become "Equipment" while the archive stays at /category/coffee-gear/.

The address only changes when you edit the Slug field. So the first question is whether you need to. A slug that no longer matches the name exactly is not a problem for search engines or visitors.

What breaks when the slug changes

For posts, core stores each old slug and redirects requests for it. There is no equivalent for terms: nothing is stored, and nothing redirects. After changing coffee-gear to equipment:

The child row is the exception. A child category's address contains its parent's slug, so renaming a parent moves every descendant archive, but WordPress looks a category up by the last segment of the path. The child is still found under the old parent path, and core redirects to its current address. The renamed category itself gets no such help.

WordPress updates what it generates itself: menus built from the category, category lists, breadcrumbs and the sitemap all use the new address at once. What it cannot update:

• links typed or pasted into post content, widgets and custom menu links;
• links from other sites;
• the address Google has indexed.

If the archive had rankings or backlinks, they are attached to an address that now returns an error.

Post URLs when categories are in the permalink

Sites using a structure like /%category%/%postname%/ have a second effect: every post in the category gets a new URL, because the category slug is part of it.

Here core does help. When a post is requested under a category path that does not exist or that the post does not belong to, WordPress finds the post by its own slug and redirects to its current permalink. So /coffee-gear/burr-grinder-review/ still arrives at /equipment/burr-grinder-review/ with a 301.

That covers the posts, not the archive. And it is one more redirect on every old link, so update internal links afterwards.

Changing a term slug safely

1. Decide it is worth it. Good reasons: a typo, a rebrand, a misleading word. Poor reason: wanting it shorter.
2. Note the old addresses, including the feed and, if the archive is long, the paginated pages.
3. Arrange the redirect before or at the moment of change. In Hydrogen SEO, switch on Auto Redirection in the Redirection Manager; it adds a 301 rule when the slug of a published post, page or term changes. Without it, add the rule by hand: old archive path to new archive path. A rule that matches everything beginning with the old path also covers the paginated pages and the feed.
4. Change the slug and save.
5. Test the old address in a private window. It should answer 301 to the new one, in a single hop.
6. Fix internal links that point at the old address. Search content for the old slug.
7. Watch for strays. A 404 monitor will show any old address still being requested, such as the feed.

If your site removes the category base so archives live at /equipment/ instead of /category/equipment/, the same steps apply. Take extra care that the new slug does not match an existing page or post slug, since they would then compete for one address.

If you already changed it without a redirect

Add the redirect now. A 404 that has been in place for days or a few weeks is recoverable: once the old address redirects, links pointing to it count again and Google updates its index on the next crawl. Check Search Console's Page indexing report under "Not found (404)" for the old addresses to confirm which ones Google has seen, and build the rule list from there with the redirect rule generator.