Dividend tax credit for charitable shareholders: proportionate corporate-tax credit on exempt dividends, with refund of any excess. Where dividends received by a charitable institution or fund are exempt, the institution shall be given a credit against its tax for dividends (excluding preference dividends) declared or distributed by a company, the credit being the proportion of the company's tax attributable to dividend distributions corresponding to the proportion of dividends received by the institution to total dividends declared or distributed by the company; any excess credit over tax payable shall be refunded, and the term relevant amount of distributions has the meaning assigned in the Finance Act of the relevant year.