Loan contracts are divided into commercial loans and private loans according to the nature of lenders. The former refers to loans issued by commercial banks or other financial institutions as lenders, while the latter refers to loans between natural persons and between legal persons and natural persons. The calculation method of overdue loan interest varies with the nature of the loan contract.

First, if the parties have an agreement on the loan term, interest during the loan period and interest on overdue loans in the loan contract, they should respect the autonomy of the parties and follow their agreement. As long as the interest rate of commercial loans overdue does not exceed the interest rate standard stipulated by the People's Bank of China and the interest rate of private loans is not higher than 4 times that stipulated by the Supreme People's Court, it shall be calculated according to the agreed interest rate.

Second, in the loan contract, the parties only agreed on the interest during the loan period, but did not agree on the interest on overdue loans. Lenders of commercial loans may require borrowers to pay overdue interest at the interest rate agreed in the contract, or they may require borrowers to pay overdue interest in accordance with relevant state regulations. The choice lies with the lender, while private loans can only require the borrower to pay overdue interest at the interest rate agreed in the contract. The reasons why commercial loans pay overdue interest at the interest rate agreed in the contract are as follows: according to the method of course explanation, it is necessary to pay the agreed interest during the loan period, and the interest should be paid at the interest rate in the period after loans overdue, that is, legal acts are still responsible for paying the agreed interest, and illegal acts are more responsible; The reason for paying overdue interest in accordance with the relevant provisions of the state is to follow the agreement according to the agreed rules, and follow the jurisprudence of the law if there is no agreement. If the parties do not make an agreement in the loan contract, they can pay overdue interest in accordance with the relevant provisions of the state.

Third, in the loan contract, the parties did not agree on the interest during the loan period, nor did they agree on the interest on overdue loans. This kind of contract is more common in private lending. There are two kinds of loans: one is regular interest-free loans, and the other is irregular interest-free loans. For fixed-term interest-free loans, the lender requires the borrower to pay overdue interest at the bank loan interest rate from the date when the repayment period expires; For non-compliant interest-free loans, the lender requires to pay interest at the bank loan rate from the time when the borrower is urged to borrow or from the time of prosecution. It is based on the provisions of Article 123 of the Supreme People's Court's Opinions on Several Issues Concerning the Implementation of the General Principles of the Civil Law of People's Republic of China (PRC) (Trial) and Articles 8 and 9 of the Opinions on the Trial of Lending Cases by People's Courts.

Second, the calculation period of overdue loan interest.

The calculation period of overdue loan interest is controversial in academic circles because there is no legal provision, and it is also a difficult problem in judicial judgment.

According to Articles 107 and 207 of the Contract Law, if the borrower fails to repay the loan within the agreed time limit, it shall not only repay the principal and pay interest on time, but also pay the overdue loan interest in accordance with the agreement or relevant state regulations. If the borrower fails to repay the loan within the agreed time limit, it shall be liable for breach of contract. Returning the principal, overdue payment of interest and overdue interest are all concrete ways to bear the liability for breach of contract. The debtor's breach of contract is also illegal, which of course damages the rights and interests of creditors. Creditors sue and ask the court to sanction the debtor's breach of contract in order to protect their legitimate rights and interests from damage. The fact that the creditor requests for adjudication should be the fact that has happened, not the fact that has not happened. The period from the overdue date of the loan to the date of prosecution is the borrower's default period; The period from the next day of prosecution to the effective date of the award is the court trial period and cannot be counted as the debtor's default period. Because the time from filing a case to the effective judgment ranges from less than one month (summary procedure) to nearly one year (extension of the trial period). If the trial period of the court is counted as the debtor's default period, then the length of the debtor's default period is in the hands of the judge. If the trial time is long, the default period will be long, and if the trial time is short, the default period will be short, which is unfair to the debtor. Someone wants to ask, not only does the lender not file a lawsuit, but the borrower will continue to bear overdue interest. After litigation, the borrower will no longer bear the overdue interest after litigation, which is unfair to the lender.

Judicial adjudication aims at resolving disputes and stopping them. The purpose of the lender's lawsuit is to ask the borrower to return the loan and loan interest within the agreed period, so as to realize the purpose of the loan contract. The court made a judgment according to the facts that have happened, forcing the debtor to repay the loan and pay the agreed interest and overdue interest, so as to end the dispute between the two parties. Lenders should carefully consider and carefully calculate whether to sue in time to repay the loan as soon as possible, or wait for the opportunity to claim compensation after the overdue interest is considerable. For lenders, the choice is not difficult.