If you are a natural person in the wages and salaries regime and have some of the following deductions:

Medical fees
Optical lenses
Medical expense insurance premiums Hospital expenses
Tuition fees in private educational institutions
Real interest accrued and actually paid for mortgage loans,
Complementary retirement contributions made in the voluntary contributions subaccount of your personal retirement plans (Afore).

You can obtain a credit balance if you present your deductions in your Annual Declaration.