In many countries, landlords can deduct mortgage interest from rental income before calculating tax. In Australia, this deduction is available in full. In the UK, residential landlords now receive a tax credit worth 20% of mortgage interest costs rather than a full deduction, following phased changes introduced in 2017. In the US, mortgage interest on rental property remains fully deductible as a business expense. Always check the current rules in your jurisdiction with a qualified tax adviser.