Rental income is subject to national income tax at a rate of 35 % that can be separated by the rental agent, or if you are not working with a rental agent, that you will have to be in charge of separating personally.
In Argentina tax is paid on all assets including real estate. This tax is calculated on the 31 of December of each year, and needs to be paid by May of the next year. It does not matter if you have owned the property for 11 months or 11 days, if you are the owner of a property on December 31 you will need to pay tax on it.
It is the responsibility of each individual property owner to remember to pay their asset tax of about 0.75 % of the property value, as the government will not send out reminders. If the tax is not paid this will only trouble you at the time of selling the property, as it can not be sold if the tax payments are not up to date, and you will have to pay a penalty for not having paid your taxes when you were supposed to.
One of the reasons that some persons might want to record a lower selling price is in order to pay a lower asset tax, since this is partially calculated based on the purchase price that is stated in the title deed.
For the general maintenance of the area you are living in you will be charged this ABL Tax by the government. This is calculated depending on the value, location, and size of your property, and you will receive a quarterly bill with the amount you need to pay, and this will usually add up to around 100 U$S / year for an average property.
This is a tax that is not applicable to the first property bought in Argentina unless the property is worth more than 200,000 U$S. If this is not the first property you are buying in Argentina, you will need to pay a Stamp tax of 2.5 of the property value.