Unfortunately, carbon offsets are often the only feasible way to truly become carbon neutral. This does not reduce the amount of carbon in the atmosphere but is a tool to help balance what we cannot eliminate right now. Carbon offsets do make a difference, even for small businesses.
This should be the last step you take toward eliminating your greenhouse gas emissions. Be sure you use reputable organizations to avoid greenwashing your conscience. As this ProPublica article reminds us, you can 
end up with a situation where “the polluters got a guilt-free pass to keep emitting CO₂, but the forest preservation that was supposed to balance the ledger either never came or didn’t last.”
Second Nature is a great resource with Frequently Asked Questions and several ways to purchase carbon offsets.
Here are a few projects to look in to: