When do I need to file as a foreign corporation?

We recently formed a c-corp in DE and are currently bootstrapping as we look for outside investment. Since we are currently based outside of DE, we will need to file as a foreign corporation at some point, but I am no sure when. It all seems to hinge on whether we are "transacting business". We are not leasing any real estate, we do not employ anyone, the owners do not take salary, and we have not made any sales as we build our product (although we do talk to potential customers who are all located in other states). Is this enough to qualify? If possible I'd rather put off the filing as long as we can to save money on the filing fee. If anyone has any experience/advice, I would appreciate it.

The answer depends on the state in which your business is operating, because different states have different tests for doing business.

Applicable laws in California and New York are discussed in When “Doing Business” isn’t “Doing Business”.

Disclaimer: This information does not constitute legal advice and does not establish an attorney-client relationship.

It depends on the laws of the countries you're operating in, selling to, shipping through, etc. Every jurisdiction has it's own rules. Know your jurisdiction, then know the jurisdiction of the area you're selling / operating in.

The best bet in almost every government is the office of industry. Second best resource are the banks (phone any bank in that region, talk to a business account specialist, boom - free advice).

It totally depends on the law of the country where you are running your business. As the law varies country to country the acts,and the fee also varies, and salary of the employees also. The best thing you can do for now is better try to concern the state lawyer,and try to get all your doubts clear as soon as possible.