The tax rules will vary depending on what country you want to incorporate and where you will operate your business. The type of entity you select will also impact this answer. If you are looking to form a corporation in the United States, then startup costs incurred prior to forming the corporation can be deducted to a certain extent, but are generally capitalized and amortized over 180 months. It's usually best to form the corporation early in the process to avoid having to amortize a lot of these expenditures. After incorporating the company, if you are not generating sufficient revenue to cover operating costs, you can certainly contribute additional funds to the corporation from your personal bank account. When shareholders contribute cash to the corporation, the contributions are classified as contributed capital. Alternatively, you could structure the contributions as a shareholder loan rather than an equity contribution. I would recommend consulting with a tax advisor to discuss your unique facts and circumstances in more detail.