I'm writing a professional business-related project summary, whereby half of the clientele is in the U.S while the other half of the same business is in the U.K. - and I don't want to disappoint either.

Question is - what shall I use between "Authorization" and "Authorisation" that doesn't make me look like I'm suffering from Dyslexia to one of the two sides?

  • 1
    Hope this will help, books.google.com/ngrams/…
    – Elian
    Oct 25, 2015 at 21:08
  • Authorixation. Sorry—in fact, there is no option between the two. You'll just have to decide which to use, or avoid the word entirely. But I doubt that using one or the other spelling will matter much.
    – herisson
    Oct 25, 2015 at 21:12
  • 2
    According to Google, the US spelling authorization occurs 1210 times on The Guardian website, compared to 4470 occurrences of authorisation. Personally, although as a Brit I'd virtually never write, say, color or honor, I don't take much notice of -isation/ization so long as I don't have both in the same utterance. Oct 25, 2015 at 21:22
  • Pick one, and try to be consistent. Any businessman with international connections will be aware that there's a difference in UK/US spellings.
    – Hot Licks
    Oct 25, 2015 at 22:00
  • Echoing Hot Licks, you should make an effort to write in either British or American English and avoid mixing them: have you never had to write "colour" or "color"? (This is assuming the people you're working for don't have a policy; many international businesses will specify the language for communications.)
    – Stuart F
    May 18, 2021 at 15:58

3 Answers 3


Use'z'. The situation is not symmetrical.

While many people in the UK prefer the 's' (and some will make a fuss about 'z' being "American"), both forms are recognised in the UK, and the Oxford Dictionaries (which are widely taken as authorities) prefer 'z'.

On the other side, I have encountered Americans who were not even aware that 's' was a possibility, and regarded it as simply a mistake.

  • 1
    Oxford's use of -ize and -ization is one of the areas where it does not reflect common current British usage
    – Henry
    Oct 25, 2015 at 21:15
  • 2
    Then it's about time they found out - i.e. that it is a possibility.
    – WS2
    Oct 25, 2015 at 21:37

As shown below, authorization is the standard AmE spelling, and it used to be also the BrE standard one till the second half of the 20th century. OED, however, appears to still favour the old (zation) spelling. Ngram shows that "authorization" is still used used in BrE so I suggest you use it to address both communities.

  • For the verb meaning to grant authority or to give permission, authorize is the standard spelling in American and Canadian English. Authorise is standard in all main varieties of English outside North America.

  • The distinction extends to all derivative words. North Americans use authorized, authorizing, authorizes, and authorization, while English speakers from outside the U.S. and Canada use authorised, authorising, authorises, and authorisation.

  • Authorize is the older form, and it was standard even in British English until the second half of the 20th century. It is in the group of Classically derived words that traditionally took the -ize ending but have recently acquired -ise. The change is not wholly engrained, though.

  • The Oxford English Dictionary, which usually favors British spellings, still lists authorize as the primary spelling, and some British publishing houses also favor the old spelling. In 21st-century edited British news publications, however, authorise appears about seven times for every instance of authorize, and authorize is even less common in 21st-century Australian and New Zealand publications.


Ngram AmE vs BrE authorization

Ngram AmE vs BrE authorisation


I think it has all been said but I'll add my own viewpoint.

  1. British spelling is a little more flexible than American spelling.

  2. You need to choose one or the other, set your word processor's spellcheck to the one you have chosen and go by that.

  3. (a) If you choose US English then you won't have any choices, the spellings are fixed. British people will assume you are American and make the mental adjustment. That's okay.

    (b) If you choose UK English then you have a little more choice. You can simply choose the US spelling where it accords with one of the British ones.

So, whatever your choice, your readers will make an assumption about you. You may as well be consistent about it. Pick and stick!

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