If you have social security, you don't need a work certificate and an income certificate, but according to the regulations, the work certificate should be stamped with the official seal of the unit, and the income certificate should be stamped with the financial seal or official seal of the unit. If you stamp another chapter, it is equivalent to not stamping it. Indiscriminate stamping not only represents the chaotic management of your company's official seal, but also makes the bank think that you are suspected of fraud.