Stephanie owns her existing main residence and decides to sell this and purchase a next main residence which comprises a house with a separate holiday cottage.
At the end of the day that is the effective date of the transaction, even though Stephanie has replaced her main residence, her purchase of an additional dwelling as part of this transaction means that she owns two dwellings. The ADS will therefore apply.
The ADS payable will, however, only be based on the consideration paid for the additional dwelling purchased and not that paid for the next main residence as a main residence has been replaced. Further details regarding how the ADS is charged in such an instance can be found in part LBTT10030 of the guidance.