Ray is selling his only dwelling which is his main residence and purchasing his next main residence. Due to mortgage complications with the purchaser of his existing main residence, this sale is delayed but the purchase of his next main residence goes ahead on time. At the end of the day that is the effective date of the transaction, Ray owns two dwellings and has not replaced his main residence. As a result, the ADS will apply.
However, if Ray sells his previous main residence at any time within an 18 month period beginning on the day after the effective date for his next main residence purchase transaction, he will be able to claim a repayment of the ADS he paid, with interest.
Details on claiming repayment of the ADS can be found in part LBTT10070 of the guidance.