23. If after the date of the application, or of the last application where more than one application are made, for registration of a firm for any assessment year and before the assessment for that assessment year is completed by the 39[Assessing Officer], so far as known to the firm, any change or changes take place in the constitution of the firm or the shares of the partners, the details of such change or changes shall be communicated by the firm to the 39[Assessing Officer] as soon as possible after each such change takes place.
