If the boss wants to apply for a loan and needs employee certification, then generally speaking, employees are required to provide relevant certification materials. The employee certificate can include payroll, social security payment certificate, labor contract and other documents, which can prove the employee's income and working status and will be helpful for the boss's loan approval. But whether it is legal or not needs to be analyzed according to specific circumstances, such as whether the privacy of employees has been leaked. In order to protect rights and avoid risks, it is suggested that bosses and employees should abide by relevant laws and regulations when handling relevant certificates to ensure legality.