21. The exemption provided for in paragraph d of section 17 ceases to have effect from the day the immoveable ceases to appear on the valuation roll as a farm or as a woodlot.
If the transferee who was granted the exemption is then still the holder of the title which devolved to him by virtue of duty-exempt transfer and less than five years have passed since the registration of the deed of transfer, the alteration to the roll shall then be deemed to be the registration of a deed of transfer within the meaning of this act and the holder of the title, the transferee of the immoveable transfereed.
Where such is the case, the officer in charge of tax collection in the municipality must, in making up the account, take into account a consideration equivalent to the market value of the immoveable at the time of the deemed transfer.
If only part of the immoveable ceases to appear on the valuation roll as a farm or as a woodlot, the rule provided in the second and third paragraphs applies to such part.