It's difficult to know without you adding your staff and business expenses, since all companies are different. To give you a starting point, the U.S. average per-capita emissions in 2011 was 17 tonnes [1], and the offset organizations we work with charge around $10 / tonne [2] [3]. So, you could expect to pay about $170 per employee per year.
The emissions per company vary wildly depending on flights and mileage driven, but for an estimate, you can assume half of your employee emissions roughly equal your corporate emissions.
[# employees] x $170 x 1.5 = Total estimate