If I received a large stock sale, is it ok to have H&R Block prepare my taxes? I just want to make sure they are capable of doing this with getting the most out of my taxes

Not in my opinion; some used H&R Block once because they had something squirrely going on, and H&R block didn't help much at all. They hire people at the beginning of tax season, and all they really do is fill in the forms online. They aren't experienced tax specialistsI recommend contact an Enrolled Agent or a CPA doing taxes in your local area for your federal/state returns;

If you have gains or losses to report from the sale of your investments, you must complete two extra forms. you usually neeed to use Form 8949 to list the investments sold and the amount of profit or loss incurred on each. The form has separate sections for long-term investments -- owned for longer than 1 year and short-term holdings. The totals from Form 8949 go on Sch D of 1040. After working through the Sch D, the final amount of gains or losses go on line 13 of Form 1040.