Beginning Saturday, Community Tax Aid of Boston will offer free tax preparation services at community centers around Boston, the nonprofit said. Individuals who earn less than $35,000 and families with incomes below $45,000 are eligible for the service. This year the organization has introduced special services for low-income small business owners, landlords, and nonresident students. Help will be available evenings and weekends from Feb. 2 to March 30 at centers in Allston, Charlestown, Dorchester, Roxbury, and the South End, with different hours and dates available at each site. More information is available on the organization’s website at www.ctaboston.org.