You will not be able to lease out the property which will be acquired for purposes of applying for the Malta CBI program for the first 5 years. You will be able to acquire an additional property and lease that out - tax will be paid at either 15% on the gross rental income, or at the progressive rates, being 0% - 35% on the net rental income (after allowing for certain deductions).
It is prohibited during the first five years after receiving a passport. You will be able to rent it out after 5 years only. The rental income is taxed in two ways (you can choose): the 15% tax on rental income applies both to residential (as from 1st January 2014) and commercial property (as from 1st January 2016); the 15% flat rate is final and no set-off or refund shall apply; the 15% is to be paid on the gross rental income; or you can declare the net rental income in your tax return and be charged with the progressive rates (0%-35%)
If you purchase a house as part of your investment program you cannot lease or rent it out until after five years. If you choose to rent the property as part of your investment program you cannot sub-lease the property, either.