TPS with a flat tax is good because one of Your expenses is not concerned. Whatever You do, pay monthly 200 UAH (or how many You have) + surcharges to the pension, and to make sure the turnover in the year was no more than the allowed amount. Well and submit reports quarterly to the tax on the movement of funds. Once a year submit reports to the pension and perepoloshit payer certificate. If memory serves, more is nothing. So do not worry, before the adoption of the new tax code nobody will be fined, but we'll see 8)