I've recently been across quite a few British sport(s) websites and Wikipedia articles and kept finding the wording "play off" show up to discuss the battle between two teams after the regular season.
In American English, I tend to think it's quite ingrained to use playoff, and that play-off is a rarer backup.
But seemed that play-off and even play off both come up more regularly in relation to British events... with play off even showing on some major sites (in the header of a Wembley Stadium Article, in a BBC Facebook post).
Google (searched from the US) shows
487,000 results for "NFL playoff" vs 17,100 for "NFL play off" compared to
62,900 for "League one playoff" vs 214,000 for "League one play off"
(The complexities of the plural form seems to further muddle things, as playoffs is a common term in the US, but perhaps not so much in the UK?). Also, Google lumps play-off and play off together under either search, and I can't find a way to overcome this?]
A quintessential comparison of the imbalance seems to be in
Even though it's just Wikipedia, it seems to follow the larger scope?
Looked into dictionaries for more info... M-W indeed found play-off, with playoff only in the unabridged dictionary... and Oxford American redirected to playoff in the American English dictionary... but was surprised to see dictionary.com favors play-off over playoff. Seems US sport league websites and even the AP style guide for the World Series use playoff without discussion. But each just seems to list one form, without mention of regional usage. Is there any site that hammers it down to that?
Alternatively, for "play off", I didn't find anything in any official capacity... and the articles with mention didn't consistently use it as separate words... so I'm thinking it's perhaps fully incorrect (outside of its valid usage as a separate phrase with unrelated meaning)? But with the range of results, and the apparent tendency for it to show up more in the UK, would welcome some further experience from the other side of the pond (or other regions) to confirm that.
[And to make matters worse, the only thread here that really touched on US vs UK hyphenation (When is it appropriate to use a hyphen) had opinion suggesting perhaps the US hyphenates more than the UK?]