As a property owner when you let your property and receive rent, this rental income is subject to tax.
Good news is there are certain expenses which can be set off against this income.

Repairs and Maintenance

Repairs and maintenance are the costs you incur to keep your property up and running. They are deductible in the year in which you incur them. Repair expenses are among the most valuable deductions tax payer can claim.

Long-Term Property Asset Expenses

Long-term assets are things you use for your rental activity that have a useful life of more than 1 year. Your main long-term asset is your home or building you rent out. However, long-term assets also include such things as furniture, appliances, vehicles, and equipment. These costs, called capital expenses by accountants, are considered to be part of your investment in your rental activity, not day-to-day operating expenses. The general rule is that the cost of long-term assets must be deducted a little at a time over several years—a process called depreciation. In Ireland rate of Capital Allowances ( tax term for Depreciation) is 12.5% which can be claimed every year rather once write off as an expense.