When two organizations merge, you keep your search rankings by mapping every old URL to its closest match on the surviving domain, redirecting with server-side 301s, and keeping those redirects live for at least a year. Redirect to real equivalents, not the homepage. Almost everything else that goes wrong in a merger traces back to skipping one of those three steps.
The short version
- Use server-side permanent redirects, either 301 or 308. Google treats a permanent redirect as a canonical signal and shows the new URL in results. A temporary 302 leaves the old URL indexed and passes nothing along.
- Map each old page to its closest equivalent on the new domain. Bulk-redirecting everything to the homepage strands the exact ranking signals you are trying to save.
- Keep every redirect live for at least a year. Google's own site-move guidance says to hold redirects that long so it can transfer all signals to the new URLs.
- Run the Search Console Change of Address tool. It requires you to own both properties on the same Google account and to 301 your old homepage to the new one.
- Expect a few weeks of ranking movement while Google recrawls and reindexes. That is normal, not a failure.
Why a brand merger is a Q4 problem, not a January one
Most rebrands and mergers launch on a clean calendar date, and January 1 is the favorite. That means the technical SEO work has a deadline of right now, in the fall, not the week of the relaunch.
The redirect map is the slowest part of a merger and the part everyone underestimates. Deciding the new logo takes a meeting. Deciding where thousands of old URLs should point takes weeks of crawling, exporting, and judgment calls, and it has to happen before the new site goes live. If you are planning a new-year relaunch and have not started the inventory, you are behind, and December is when board reporting and year-end giving will take the attention this work needs.
The mechanics are knowable, at least. I am in the middle of a two-domain consolidation for a B2B software brand right now, and I have run smaller versions for a regional association that merged with a sister organization. Nothing changes with the size of the org except the number of rows in the spreadsheet.
Start with a page inventory, not a redesign
The first deliverable in any merger is a full inventory of every indexed URL on both sites, ranked by the traffic and links it earns.
Crawl both domains, export the URL list, and pull organic landing-page data from Google Analytics 4 (GA4) and Search Console for the last twelve months. Cross-reference against your backlink profile so you know which pages other sites actually link to. The output is a single sheet: every old URL, its traffic, its inbound links, and a blank column for its destination on the new domain. That blank column is the entire project. I score pages before I migrate anything so the high-value URLs get individual attention and the dead weight gets handled in bulk, a method I wrote up in page scoring for domain migrations.
Skip this step and you will discover, three months after launch, that a single resource page which quietly drove a third of your organic donations was redirected to nowhere in particular. By then the rankings are gone and recovery is slow.
Map redirects one to one, to the closest equivalent
Every old URL that had value should redirect to the single new page that most closely matches what it was about. Not the homepage. Not a generic category page. The closest real equivalent.
This is the mistake I see most often, and it is always framed as a shortcut: "just point the old domain at the new homepage and we'll sort the rest later." It never gets sorted later. Redirect a well-linked program page to your homepage and you are telling Google the old page's topic is now your homepage's topic, which is not true, so the equity dissipates instead of transferring. A page-to-page redirect tells Google the new page is the direct replacement, and the permanent redirect acts as a canonical signal toward it. That is the whole mechanism you are relying on. Do not break it to save an afternoon.
For the long tail of URLs with no traffic and no links, a sensible catch-all is fine. For anything that earns traffic or links, map it by hand.
Use 301s, server-side, and nothing weaker
For a permanent move, use a permanent redirect, and implement it on the server. Google recognizes several redirect methods but ranks them by how reliably it can interpret them: server-side redirects are the strongest, meta refresh weaker, JavaScript location redirects weaker still, and Google's guidance is explicit that you should only use JavaScript redirects if you cannot do server-side or meta refresh. In practice the redirects belong in your server or CDN configuration, not bolted on with a plugin or a client-side script. A 308 works the same as a 301 here. A 302 is temporary, which tells Google to keep the old URL in results and treat the move as reversible, the opposite of what a merger is.
Run the Change of Address tool correctly
When you are moving between domains, tell Google directly with the Search Console Change of Address tool.
The requirements are specific. You must be a verified owner of both the old and new property, under the same Google account, and both must be domain-level properties. Before you run the tool, you must already have a 301 from the old homepage to the new homepage. The tool does not replace your redirects. It runs on top of them and helps Google process the move faster. Submit your new sitemap in Search Console once the new URLs are live, and remove the old one.
Keep the redirects for a year, and keep paying for the old domain
Do not tear the redirects down the month after launch, and do not let the old domain lapse.
Google's site-move documentation recommends keeping redirects in place for at least a year so it can transfer all signals to the new URLs. The Change of Address tool's own guidance is to maintain them for at least 180 days, longer if you still see any Search traffic, after which Google stops recognizing a relationship between the old and new sites. A year is the safe number. Google also recommends paying for the old domain for at least a year, because an abandoned domain with inbound links is a target for someone to buy and misuse. For a merged organization, letting the retired brand's domain expire is not just an SEO risk, it is a reputational one.
What this does not cover
This playbook is about protecting organic search through a domain change. It does not cover the rest of the merger.
It does not address migrating paid search campaigns, email sending domains and authentication, or social handles, each of which has its own transfer steps and failure modes. It does not cover the editorial work of deciding which of two overlapping content libraries survives, which is a strategy call, not a redirect. And it does not apply to same-domain changes like www to non-www or HTTP to HTTPS, which still need 301s but do not use the Change of Address tool, because Google does not treat those as a move to a new site.
What to expect after launch
Rankings will move in the first few weeks, and that movement is not evidence you did something wrong. Google has to recrawl and reindex both sites, and its own guidance notes fluctuations during that window, with medium-sized sites often taking a few weeks or more to settle. Watch Search Console's coverage and performance reports, keep an eye on the redirect target pages, and resist changing things on day ten because a few queries dipped. The signals you mapped will transfer, just not instantly.
FAQ
Should I redirect old pages to the new homepage?
No, except for genuinely valueless pages. Redirect each old URL that earns traffic or links to its closest equivalent on the new domain. Homepage redirects do not transfer the old page's topical relevance, so the rankings you wanted to keep dissipate.
How long do I keep the redirects in place?
At least a year. Google's site-move guidance recommends keeping redirects live long enough to transfer all signals, generally at least one year, and to keep paying for the old domain for at least that long as well.
Should I use a 301 or a 302 for a brand merger?
A 301. A merger is a permanent move, and only a permanent redirect (301 or 308) tells Google to show the new URL and treat it as canonical. A 302 is temporary and leaves the old URL in search results.
Will we lose rankings during the migration?
Expect temporary fluctuation. Google recrawls and reindexes both sites over a few weeks, and some movement is normal. Clean one-to-one 301s and a correctly run Change of Address process are what get rankings back to where they were, or better.
Do we need the Change of Address tool for a www to non-www change?
No. The tool is for moving between domains or subdomains. A www to non-www or HTTP to HTTPS change still needs 301 redirects but does not use the tool, because Google does not treat it as a move to a separate site.
If you are planning a merger or rebrand relaunch for the new year, the redirect map decides whether you keep your traffic or start over. I will inventory both sites, score the pages, and build the migration plan before your relaunch date. Book a 30-minute migration review and we will look at your two domains together.