以房抵债合同的性质及效力
甲向乙借款，乙防止甲不能还款，要求甲提供相应担保，甲用自己的房子和乙签订商品房买卖合同为借款提供担保，当甲不能按时还款时，甲的房子归乙所有，乙借给甲的钱就当做买房子的钱。上面那个例子就是以房抵债合同。
以房抵债合同订立在债务履行期届满前，实质是非典型担保合同。典型担保合同是指为促使债务人履行其债务，保障债权人的债权得以实现，而在债权人（同时也是担保人）和债务人之间，或在债权人、债务人和第三人（即担保人）之间协商形成的，当债务人不履行债务或者无法履行债务时，以一定方式保障债权人债权得以实现的协议。它与一般担保合同的区别就是除担保合同之外，还签订了一份房屋买卖合同，一般的担保合同是只有一份担保合同，而不再存在别的合同。
以房抵债合同订立后，一般认定为担保有效，但债务人不得基于该合同主张转移房屋所有权，就是以房抵债的那个条款无效，但是不影响担保合同的效力。（上面那个案例中，甲提供的担保有效，但是乙不能因为与甲签订了商品房买卖合同就能得到房子的所有权，因为甲与乙签订的以房抵债的条款属于担保法的禁止性规定）。《担保法》第40条规定：“订立抵押合同时，抵押权人和抵押人在合同中不得约定在债务履行期届满抵押权人未受清偿时，抵押物的所有权转移为债权人所有。”这是抵押合同的禁止。
如果以房抵债合同签订在债务履行期届满后，实质是为债务履行方式变更协议，一般也认定为有效，债权人可以基于该合同主张转移房屋所有权。（在上面那个案例中，如果甲和乙签订的以房抵债合同是在甲和乙签订借款合同，甲不能及时还款后，再签订的，这时乙就能够取得房屋的所有权。如果房屋的价值超过甲的价款时，甲可以要求乙归还超过借款部分的钱）但如果债务人认为房屋价值远超欠款，可以主张合同撤销。（在上面那个案例中，甲如果认为房屋的价值远远超过借款时，甲也可以主张撤销商品房买卖合同，归还乙借款）
The nature and validity of the house-debt contract
A borrows money from B,
B prevents A from being able to repay, and asks A to provide corresponding（相应的）guarantees. A signs a commercial0 house sales contract with his house and B to provide guarantee for the loan（借款）. The money lent to A is used as money to buy a house. The example above is a house-debt contract.
The conclusion of a house-debt contract before the expiration（届满，期满）of the debt performance period is essentially an atypical（非典型的）guarantee contract. A typical guarantee contract refers to the negotiation between the creditor （债权人）(also a guarantor) and the debtor（债务人、借方）, or between the creditor, the debtor, and a third party (that is, the guarantor) in order to promote the debtor to fulfill its debts and protect the creditor ’s claims（债权、请求）. An agreement is formed（产生、形成）to protect the creditor ’s claims in a certain way when the debtor fails to perform the debt.The difference between it and the general guarantee contract is that in addition to the guarantee contract, a house sales contract is also signed. The general guarantee contract is that there is only one guarantee contract, and no other contract exists.
After signing a house-debt contract, generally recognized that the guarantee contract is valid. However, the debtor shall not claim to transfer the ownership of the house based on the contract, that is, the clause（条款）of the mortgage（抵押）debt is invalid, but does not affect the guarantee contract Effectiveness.(In the above case, the guarantee provided by A is valid, but B cannot obtain the ownership of the house because of the contract for the sale of a commercial house with A, because the terms（条款）of debt settlement by A and B are prohibited by the guarantee law).Article 40 of the "Guarantee Law" stipulates（规定）: "When entering into a mortgage contract, the mortgagee and the mortgagor shall not stipulate in the contract that the ownership of the collateral（抵押物）shall be transferred to the creditor when the mortgagee has not been paid off at the end of the debt performance period." This It is the prohibition of mortgage contracts.
If the house-debt contract is signed after the expiration of the debt performance period, the essence is to change the agreement for the way of debt performance, it is generally also deemed valid, and the creditor may claim to transfer the ownership of the house based on the contract. (In the above case, if a house-debt contract signed by A and B , is signed after A and B have signed a loan contract, and A cannot repay, then B can obtain ownership of the house. When the value exceeds the price of A, A can ask B to return more money than the borrowed part). But if the debtor believes that the value of the house is far more than the arrears（欠款）, it can claim the contract to be cancelled. (In the above case, if A thinks that the value of the house is far more than the loan, A can also advocate the cancellation of the commercial house sales contract and return the loan of B)