A payroll savings plan is an automatic method of purchasing savings bonds. (See the definition in Sec. 363.6.) You may open your payroll savings plan by selecting an amount, series, and registration for your savings bond purchases using functionality in your TreasuryDirect[supreg] account. Each bond purchase must be in a minimum amount of $25 with additional one-cent increments above that amount, up to a maximum amount of $5000, in any one transaction. The series may be either a Series EE or Series I savings bond. The registration may be any authorized form of registration for an electronic savings bond. You must also initiate a request to your employer or your financial institution to send credits on a recurring basis to your payroll savings plan through the ACH method to purchase a payroll zero-percent certificate of indebtedness. (See Subpart D for more information about a payroll zero-percent certificate of indebtedness.) When you have accumulated a sufficient amount of payroll zero-percent certificate of indebtedness to purchase a savings bond in the amount, series, and registration that you selected, the TreasuryDirect[supreg] system will automatically redeem your payroll zero-percent certificate of indebtedness and purchase your selected savings bond. [75 FR 70816, Nov. 19, 2010]