In what term is the underpayment amount of levy for a one-time (special) voluntary declaration, which arose as a result of the internal audit, paid?

Sub-paragraph 15.1 Paragraph 15 Sub-section 9⁴ Section XX “Transitional Provisions” of the Tax Code of Ukraine stipulates that in case of detection of an arithmetic error, which led to the underpayment of levy for one-time (special) voluntary declaration by the central executive body implementing the state tax policy, based on the internal audit results of relevant one-time (special) voluntary declaration, the declarant who submitted relevant one-time (special) voluntary declaration is obliged to pay amount of such underpayment within 10 calendar days from the date of receipt of relevant notification in any form of the central executive body implementing the state tax policy and submit a clarifying relevant one-time (special) voluntary declaration within 20 calendar days from the date of receipt specified notification.