The tax department where the house is located. According to the enquiry of China Travel official website. Com, the tax authority is the invoice authority, the purchase invoice is issued by the real estate company, and the real estate company uniformly issues the invoice at the tax authority where the house is located. Therefore, the purchase invoice can be found in the tax department where the house is located. The purchase invoice is the proof of the down payment, which can be used to prove the down payment.