Most popular tax preparation software: Some of probably the most popular tax preparation software contains TurboTax, H&R Block, TaxAct, TaxSlayer, FreeTaxUSA. atOptions = { 'key' : 'a8dfc29b76f8e0e43144f40c1f6e4e79', 'format' : 'iframe', 'height' : 90, 'width' : 728, 'params' : {} }; document.write('');