How long should you keep the old site online after a domain migration?

Why does Google emphasize maintaining the old domain?

When a site changes its domain, search engines do not instantly transfer all signals to the new address. 301 redirects, although intended to be permanent, trigger a consolidation process that takes time.

Google needs to recrawl each URL of the old domain, follow the redirect, understand that the content has been permanently moved, and then gradually transfer authority, backlinks, and history to the new domain. This process is neither linear nor uniform: some pages may be consolidated in a few days, while others may take several weeks.

What actually happens during this transition phase?

Google's crawlers will regularly visit the old domain to check the stability of the redirects. If the old site disappears too early, Google may interpret this as a signal break and not complete the transfer of PageRank.

The necessary duration depends on several factors: the size of the site, historical crawl frequency, the volume of backlinks pointing to the old domain, and the technical structure of the migration. A small site may consolidate its signals in a few weeks, while a site with thousands of pages may take several months.

What is the recommended duration for keeping the old domain active?

Matt Cutts mentions a “long period” without specifying an exact timeframe. Based on field observations, a minimum period of 6 to 12 months is generally necessary for medium to large sites.

Some professionals keep the old domain active for 18 to 24 months for high-authority sites to ensure that all SEO signals have been properly transferred. This caution also helps to manage backlinks that are slow to update and old URLs still present in external resources.

• Minimum recommended period: 6 months for a small site, 12 months for a medium to large site
• Determining factors: volume of pages, historical crawl frequency, number of incoming backlinks
• Main risk: premature stopping of redirects before complete signal consolidation
• Monitoring needed: monthly tracking of traffic, positions, and crawl signals in Search Console
• Special case: for e-commerce or media sites with significant history, consider 18-24 months

Is this recommendation consistent with observed practices in the field?

Yes, and field data confirms that poorly managed domain migrations result in organic traffic losses ranging from 20% to 60% in the initial months. Keeping the old domain active helps cushion this drop and smooth the transition.

However, Google remains vague about the exact duration. The expression “long period” is deliberately ambiguous. [To be verified] In practice, observations show that the technical quality of the migration matters as much as the duration: a site with chained redirects or intermediate 404 errors will gain nothing from keeping the old domain for 12 months.

What nuances should be added to this guideline?

First, maintaining the old domain does not mean continuing to publish content on it. The site should be frozen, with all URLs redirecting 301 to the new domain. If Google detects fresh content on the old domain, it may consider it two distinct sites.

Secondly, this recommendation assumes that the old domain has a good reputation. If the original domain has been penalized or has a toxic link profile, keeping it active could transfer these negative signals to the new domain. In this case, a clean break might be preferable.

In which cases does this rule not strictly apply?

For new domains without SEO history, the question does not arise: there is no migration in the strict sense. Similarly, for a complete rebranding where the old brand disappears, keeping the old domain may create confusion and dilute the identity of the new site.

Very small sites (fewer than 50 pages) with few backlinks and sporadic crawling may afford a shorter period, around 3 to 6 months, without major risk. Finally, if the old domain expires and is bought by a third party, it is better to let it go than to keep it artificially.

What should you do concretely during a domain migration?

First and foremost, map out all the URLs of the old site and prepare a comprehensive redirect plan. Each URL must redirect to its exact match on the new domain, not to the default homepage.

Set up 301 redirects at the server level (via .htaccess, nginx.conf, or a CDN rule), test them in batches with tools like Screaming Frog, and ensure there are no redirect chains. Once the migration is launched, declare the address change in Google Search Console and monitor index coverage reports.

What mistakes should you avoid during this transition period?

The first mistake is to let the domain renewal lapse before the end of the consolidation period. If the old domain expires and someone else buys it, you lose all control over the redirects and historical backlinks.

The second common mistake is changing the redirects along the way. Once Google has started consolidating signals, changing the target URLs of the 301s may reset part of the process. Finally, do not touch the robots.txt or sitemap of the old domain: let Google crawl freely so it can see for itself that everything has been moved.

How can you check that the migration is going well?

Monitor the organic traffic evolution on the new domain in Google Analytics each month and compare it to the historical data of the old one. Watch for impressions and clicks in Search Console to detect any abnormal drops.

Also, check that Google continues to crawl the old domain (under “Crawl statistics” in Search Console): if the crawl drops sharply before your positions stabilize, that’s a warning sign. Finally, regularly audit incoming backlinks with Ahrefs or Majestic to see if links start pointing directly to the new domain.

• Prepare a complete mapping of URLs before migration
• Set up 301 redirects at the server level, without chains
• Declare the address change in Google Search Console
• Keep the old domain active for a minimum of 6 to 12 months
• Monthly monitor traffic, impressions, and positions
• Do not change the redirects once migration has begun