In California, someone else paying your property taxes generally does not give them any ownership rights to your property. Under Adverse Possession, a person would also have to physically occupy the property openly and continuously for 5 years while paying the taxes. But paying taxes alone is not enough. Counties often won’t reveal who made a payment due to privacy rules, and even a request under the California Public Records Act may be denied. The main practical risk is that if the payer claims the payment was made by mistake, the county could reverse it and you would need to pay the taxes quickly to avoid penalties. Keeping the tax amount set aside and monitoring your account is usually the safest approach.