In your situation tpcp, that is a smart thing to do. If your job is supplying your needs, then the only way to build your business is to keep putting the money back into the business. Like vangogh said, do without so it won't always be that way. The thing that separates business owners from consumers is their willingness to practice "delayed gratification."

I agree that a percentage may not be the answer to this question. To say "as much as possible" may seem simple, but that the most appropriate answer. Don't ignore that putting back into the business should include a savings buffer to get you through any dry spells.