Can I use the specific identification method for the sale of stock this year even though I used FIFO for sales of the same stock in the past?

Yes. The specific identification method allows you to use the cost basis of the shares you sell to figure your gain or loss. FIFO, or first-in, first-out, is the default method for figuring basis if you do not instruct your broker or agent to use the specific identification method. You can override FIFO at any time buy giving directions to your broker; get a written confirmation that you are using the specific identification method.