In 2009, the company;s accountant discovered that dpreciation expense in 2008 for the office building was overstated by $300,00.

Building represent the corporate headquarters and manufacturing facilities; How do I account for the $300,000 on the Income Statement?

You don't. It's a prior period adjustment which isn't on the income statement. It's adjusted to the beginning 2009 balance of retained earnings. That way, retained earnings is corrected from 2008 as it should be, and an adjusted retained earnings starts off the year. That leaves the income statement for only the current year as usual.