Two major tax and benefits reforms were implemented in 2007 in Poland. In the first one a rate of disability contribution for social insurance was lowered form 6.5% to 4.5% while a tax child credit in an amount of 1145 PLN was introduced in the second one. A paper compares implementation costs for these and some other potential tax and social security reforms as well as presents some distributional consequences of the reforms. Potential reforms include: flat-tax reform with a 18% tax rate, two tier personal income tax system with 18% and 32% rates, rising an amount of revenue costs for a permanent employment. The results obtained by using a tax-benefit microsimulation model SIMPL showed that the rising a revenue costs for a permanent employment would have been the most efficient reform in terms of lowering the at-risk of poverty rate. It is shown that introduction of a child tax credit of 1145 PLN in 2007 was not an effective anti-poverty policy.