Happy New Year!
The usual ‘happy new year’ is “akemashite omedetougozaimasu”
Or more casually, akemashite omedetou/あけまして おめでとう！
Some people shorten it even more to akeome/あけおめ.
But this is only used after the New Year has happened.
That’s because akemasu means to open and is only used after the new year has ‘opened’.
If you want to say happy new year before January 1st you should say yoi otoshi o omukaekudasai/よいお年をお迎えください.
Or more casually, yoi otoshi o/良いお年を.
It just means may the next year be good.
Even though it’s still called 2014 Japan. They still count years based on eras as well.
But because the previous emperor died on the 8th of January the new era started then.
So, it won’t be Heisei year 26 until January 7th.