The Tax Office has several methods to know if a house is occupied or not. First of all, the tenant is obliged to indicate his habitual address when he makes the income statement, which is suspicious if he is living on a rent without a contract. About the owner, he must record in the same declaration all the properties that belong to him and if they are available or rented. There is also the possibility that it is the tenant himself who declares the rent to benefit from the tax deductions that correspond to him. And finally, the consumption of electricity and water are also a clear indicator, since the Tax Office has free access to these data.

So, if the Tax Office discovers you, you need to know that the owner of the property will be penalized for having hidden the income corresponding to the lease and, in case that the tenant has benefited from the refund corresponding to the tax deductions, will also be sanctioned. In both cases must be paid to the Treasury:

- The amount of the benefits obtained.

- The interest for delay that corresponds since the beginning of the economic activity.

- The sanction.

- They will lose any option to benefit from tax deductions.

As you can see, it's better to do things correctly and avoid risks.