Google responds to the question of how long 301 redirects should be kept in place after a site move, stating that a year is the minimum recommended time.
Why a whole year?
Because it takes Google time to process a major change such as a site move.
If redirects are in place for less than a year, Google may not crawl the links enough times to recognize that the site has been permanently relocated.
This topic is highlighted in the most recent installment of YouTube’s Ask Googlebot video series.
How Long Should I Keep A Site Redirect For?
Google’s Search Advocate John Mueller responds to the above question by first clarifying that 301 redirects are appropriate in this case.
People use two types of redirects on their websites: 301s and 302s.
A 301 redirect indicates to Google that a page has been permanently moved, whereas a 302 redirect indicates a temporary page move.
Because a site move is a permanent change, 301 is the appropriate redirect to use.
Given the web’s constant evolution, you may be wondering if “permanent” really means “permanent.”
“At Google we try to reprocess all pages at least every few months. Most pages are checked more often. However, the amount of crawling is limited and there are many pages that we’d like to crawl, so we have to prioritize.
When a URL changes our systems need to see the change in the form of a redirect for at least a few times in order to record that change.
To be certain that a redirect has been seen a few times, we recommend keeping the redirect in place for at least one year.”
When it comes to site migrations, it’s not as simple as simply redirecting the old domain to the new domain.
You must configure 301 redirects from each individual page on the old site to the corresponding page on the new site.
If there are pages on the old site that you do not intend to keep, you do not need to redirect them to a new URL.
It’s also critical to update any references to the old URLs, such as external links.
To be clear, it is perfectly acceptable to leave redirects in place for longer than a year. You can leave them up for as long as you want.
A year is the bare minimum length of time to keep 301 redirects in place to reduce the potential negative impact a site move can have on your SEO.
Learn more from SEO and read 7 Local SEO Updates for 2021 That Will Impact Your Strategy.