If the tax investigation is true, you must admit that you violated the accounting system and the relevant provisions of the tax law, but don't admit the punishment yet.

Law of the People's Republic of China on the Administration of Tax Collection Article 70 If a taxpayer or withholding agent evades, refuses or otherwise obstructs the inspection by the tax authorities, the tax authorities shall order him to make corrections and may impose a fine of less than 10,000 yuan; If the circumstances are serious, a fine of not less than ten thousand yuan but not more than fifty thousand yuan shall be imposed. As long as you don't have the above behavior, there is absolutely no basis for paying 50,000 yuan. Pretend to admit the punishment and ask him for a written basis. If you can't take it out, you won't give it to him. If he wants to impose a hard punishment, he will apply for administrative reconsideration or bring an administrative lawsuit to the court.