Yep it is declared as income.
but you can claim against - insurance, rates, water, repairs, agent fees and interest repayments.

What ever is left over then you have to pay tax on.

also double check how long you have lived in the property and how long it was an investment (rented) because this can also affect you when it comes time to sell - capital gains etc, as there is a limit of time that turns the property no longer into your principal place of residence - thus more taxes when you sell

HTH
Best to have a chat to an accountant to sort it out for you in preparation