CFR > Title 31 - Money and Finance: Treasury > SUBTITLE B—Regulations Relating to Money and Finance > CHAPTER II—FISCAL SERVICE, DEPARTMENT OF THE TREASURY (parts 200 to 391) > SUBCHAPTER B—BUREAU OF THE PUBLIC DEBT (parts 306 to 391) > PART 363—REGULATIONS GOVERNING SECURITIES HELD IN TREASURYDIRECT > SUBPART B—General Provisions Governing Securities Held in TreasuryDirect (§363.7-363.8 to §363.48-363.49) > 363.21—When may you require offline authentication and documentary evidence?