This is certainly possible, though not necessarily simple.
Residential mortgages and buy-to-let mortgages are very different. Residential mortgages are designed to offer protection to home owners and are regulated by the Financial Conduct Authority to reduce the risk of the mortgage holder(s) losing their home. Buy-to-let mortgages are not regulated by the Financial Conduct Authority and involve different affordability calculations and criteria.
Buy-to-let mortgages are calculated based on the rental income the property is likely to achieve and usually interest-only. Therefore, any discussion with the lender of an existing residential mortgage regarding changing to buy-to-let will usually involve an entirely new application process.
There is an exception for temporary periods of letting, whereby a residential mortgage holder can apply for ‘consent to let’ for a time-limited period.
If you are considering turning your current home into a buy-to-let property, it is best to speak to your mortgage lender as early as possible to ensure that you do not breach your existing mortgage in any way. You will also need to speak to your insurance company regarding amending your home insurance.
*The information provided should not be taken as financial advice in relation to the UK property market or property investment advice.