Interim Corp. Tax Return
Every incorporation should file and pay the interim corp. tax return by the end of Aug., you can just pay half of the amount you paid on the last end of March, or can file and pay taxes based on your own calculation.
But if your corporation was established in this year or your fiscal year was not ended by the end of Dec., you don't need to file this time.
If you needed to pay more than 10mil.won, you can pay installment method by an application.
More questions, please feel free to contact me at firstname.lastname@example.org