Use the Welsh Revenue Authority web link for LTT (Land Transaction Tax). Their Calculator is easy to use
You are Higher Rate if you already own property anywhere in the world or purchase in your limited Company name.
Exemptions and Reliefs may apply. Take appropriate advice. Such advice is not via your Conveyancer. Speak to a Tax specialist.
Bear in mind - it is your responsibility to pay Duty and submit the return and NOT your Conveyancer. The contents of the Return are your responsibility and will be based on your instructions to your Conveyancer. They act as agent only.
If you sell your pre-existing property within 3 years you can make a claim for reimbursement of the higher rate duty you paid. You do not need to instruct anyone to do that for you. This can be done online with the Welsh Revenue Authority.