Write a letter to the head of the company. In the appeal, specify the following information: for the purpose of obtaining information (e.g. for credit); the period for which you need to obtain information about income. After that, register the application in the incoming correspondence log and give the document to the employer.
Within a certain period of time, which you can discuss with the supervisor, you will receive an income statement (form №2-NDFL). Check the correctness of its filling, it should have the name of the organization, your data, data on incomes, company seal and signatures of the employer and the chief accountant.
If the company where you worked, is liquidated, you can get help in court. For this you need to go to court with a lawsuit. In the request specify the purpose of reference, period of work in the organization. If you have supporting documents to receive wages (for example, settlement statements), attach them to the suit. You also need to provide an employment contract concluded with the employer. If these documents are not, find witnesses (former colleagues).
If you are an entrepreneur, you can get help at the tax Inspectorate in which you are registered. For this you need to write a letter (sample pick instance). After five calendar days, you will be able to get the information you need. If for any reason you do not have the opportunity to come for help, receive it in the mail. But for this you need the statement to specify the address and name of the recipient.
If someone offers you to get fake proof of income for little money, give up, because this face criminal liability.