26 C.F.R. § 1.118-1
In the case of a corporation, section 118 provides an exclusion from gross income with respect to any contribution of money or property to the capital of the taxpayer. Thus, if a corporation requires additional funds for conducting its business and obtains such funds through voluntary pro rata payments by its shareholders, the amounts so received being credited to its surplus account or to a special account, such amounts do not constitute income, although there is no increase in the outstanding shares of stock of the corporation. In such a case the payments are in the nature of assessments upon, and represent an additional price paid for, the shares of stock held by the individual shareholders, and will be treated as an addition to and as a part of the operating capital of the company. Section 118 also applies to contributions to capital made by persons other than shareholders. For example, the exclusion applies to the value of land or other property contributed to a corporation by a governmental unit or by a civic group for the purpose of inducing the corporation to locate its business in a particular community, or for the purpose of enabling the corporation to expand its operating facilities. However, the exclusion does not apply to any money or property transferred to the corporation in consideration for goods or services rendered, or to subsidies paid for the purpose of inducing the taxpayer to limit production. See section 362 for the basis of property acquired by a corporation through a contribution to its capital by its stockholders or by nonstockholders.
26 C.F.R. §1.118-1