In Tag Folksonomy and Tag Synonyms, I read this sentence:
We’ve also slowly but surely been increasing the reputation required to create a new tag from 250 reputation, to 500 reputation, all the way to the current setting of 1500 reputation.
But I added a new tag successfully on Meta just a moment ago. However, my reputation here is only 768.
Is this a bug?
Compare the Create Tag privilege pages on MSO and SO, and also check out the page on SU as well and you can see that these are site specific values (500, 1500 and 200 respectively for those examples).
Basically, the increase you are reading about only applies to Stack Overflow, not MSO or any other site.
You might find the Reputation requirements compared post useful.
To see if you have the privilege of doing something, you should check what reported in the privilege page, whose link is reported in the drop-down menu that pop ups when you hover the mouse over your username on the top of the page.
If you see that, for a privilege, the required reputation is higher than the reputation you have, then it could be a bug, or the description for the privilege is not correct, or you didn't understand correctly what the privilege being described is.
In fact, privileges and limits being used on a site could change from site to site. To make an example, on Stack Overflow you can vote to close 50 questions per day, but in other sites (including this very meta site) that limit is 24.
Sometimes limits are changed on a specific site basing on particularly necessities; the limit on the number of questions you can vote to close has been increased on Stack Overflow because probably there are many questions that needed to be closed, but that were not closed.
