You may have a stamp duty liability if you change your ppr into an investment property less than five years after purchase, depending on what you paid in the beginning. A good browse through these pages shoudl answer your questions. Also - is the original property in a good rental area? Being a landlord is getting more difficult - tenants are getting more discerning - it's no longer the path to instant gold! But if your house is in a good area and good condition you should be okay. Also consider the CGT liability if in the future you see yourself selling both properties to buy that dream home.