There is no documents required to start a sole proprietorship firm. A person can start proprietorship business in his own name and he can choose a name for his business.
He is required to keep record of all the transactions of his business, popularly known as accounting records. These records include cash book, ledger, journal, sales register, purchase register etc. He is required to get his accounts audited from a chartered accountant once his total turnover during a financial year exceeds Rs. 60,00,000/-.
A sole proprietorship firm shall require a TAN number once it is legally required to get his accounts audited. So long as it is not required to get his accounts audited, i.e., its turnover does not exceed Rs. 60,00,000/- TAN number is not required for it and it is legally not liable to deduct TDS for the payments made to parties for expenses.