← All entries Exhibit 126 · Website IRS: Understanding your letter 6167C IRS A previous year’s income tax return, other than the year in the letter (Form 1040, 1040-A, 1040-EZ,1040-PR, 1040-NR, etc.). 1 double space marked in red. Copy the quote and you'll get the real spaces too. Open the full-size photo in a new tab.