The agreed time limit of real estate mortgage mentioned here is actually the time limit for the performance of the secured principal creditor's rights. Because the debtor fails to perform the debt as agreed, the mortgagee has the right to exercise the mortgage.

When the performance period of the principal creditor's rights expires, there is no need to apply for extension of registration immediately. Because mortgage, as a kind of real right, can only be destroyed by the performance of debt, the exercise of mortgage or the loss of collateral.

Article 12 of the Supreme People's Court's Interpretation on Several Issues Concerning the Application of the Security Law of People's Republic of China (PRC) stipulates: "After the limitation of action for the creditor's rights secured by the security interest ends, if the secured party exercises the security interest within two years after the limitation of action ends, the people's court shall support it." Although the judicial interpretation does not determine that the mortgage is invalid two years after the limitation of action for the principal creditor's rights ends, according to the provisions of the Guarantee Law, the mortgagee may agree with the mortgagor to be compensated by discounting the collateral when the debt is not paid off at the expiration of the performance period. If the agreement fails, "the mortgagee may bring a lawsuit to the people's court". In other words, many people may exercise this right through legal proceedings. If the people's court does not support this claim, the interests of the mortgagee will be harmed.

Therefore, the extension of registration should be handled before the expiration of this period. This registration should be determined according to the agreement of the parties, such as changing the performance period of the principal creditor's rights, or re-setting the guarantee by repaying the loan as a new creditor's right. The registration authority may register according to the application of the parties concerned.

Real estate mortgage is an independent civil act between mortgage parties. When the agreed real estate mortgage period expires, the mortgagor decides whether to extend the registration and choose to exercise the mortgage right, or neither to extend the registration nor to exercise the mortgage right. The registration agency neither intervenes nor assumes any responsibility for this.