새해 복 많이 받으세요 [ saehae bok mani badeuseyo ]
새해 means ‘new year’, 복 ‘good luck’, 많이 ‘a lot’, and 받으세요 ‘get / take please’. This expression is frequently used among Koreans around January and February, wishing the listener’s great and flourishing New Year. It is the same way as ‘Happy New Year’.
To family members and friends or even to clerks and taxi drivers, if you can say this, they will be really happy and say it back to you.