TaxHawk and FreeTaxUSA are identical except for the name and styling differences. An account in one carries over to the other. Uses a mixture of interview and form entry process. I liked the ability to bookmark sections.

Navigating was accomplished by tabs at the top but was limited to entire sections of the return, e.g. the entire Itemized Deductions Schedule A section. No form navigation provided.

Mixture of interview and form input. Many of the screens mimic the forms. The program is noticeably quicker than others, e.g. less of a delay between completing one screen before the next appears.

TaxHawk owns both sites.

If you have a 1099R with taxable unknown and employee contributions then you must calculate the simplified method yourself. They do refer user to appropriate IRS publication.

Doesn't calculate whether state tax refund is completely taxable (does ask questions to determine if some was taxable and does provide a pdf worksheet to calculate the taxable part).

Doesn't calculate estimated state sales tax for Schedule A but clicking the "?" does provide a link to the IRS Sales Tax Deduction Calculator.