If you move the lender cannot change the original terms of the mortgage agreement. So if for example, you buy a new house, and turn your old one into an investment property you will still have the benefit of the original interest rate when you financed it as owner occupied. For many people this is the easiest way to get into owning investment properties.

It is possible to move into one of your rental or investment properties and, for tax purposes, convert it to your primary residence. This could effectively remove the tax liabilty based on the appreciation in value and depreciation you have claimed on that home. Consult with your tax professional to find the details of how to accomplish this.

If you are moving and changing the status of an investment property or second home into your primary residency you may want to look into refinancing. A Primary residency represents less risk to the lender because if times get rough you are more likely to make payments on your primary residence compared to a vacation or investment property you may have. Since they are less risky they have lower interest rates.

Some borrowers will intentionally lie about their occupancy in the home to get a better rate. If the lender finds out about this, they can accelerate the loan and demand payment in full, or they may choose other options. Lying on your loan application is fraud, and could get you in a lot of trouble. The best advice is to always be truthful about your intentions.