I used turbo tax to e-file my Federal and I was told a few days later that I needed to sign form 8453-OL and mail it in to finish my filing. I couldn't print my report at the time I sent the forms through turbo tax, so when I was given this message I printed a blank form 8453-OL from the IRS website, filled in my DCN (declaration control number) and signed as instructed. Although the IRS has my information through turbo tax, is it necessary that I fill out the details of 8453-OL before I send it in?