Automatic IRA Act of 2015

Amends the Internal Revenue Code to: (1) require certain employers who do not maintain qualifying retirement plans or arrangements to make available to their eligible employees a payroll deposit individual retirement account (IRA) arrangement (automatic IRA arrangement) which grants such employees the right to opt-out of participation; (2) require the Secretary of the Treasury to provide employers with a model notice for notifying employees of their opportunity to participate in an automatic IRA arrangement and to provide participants with an annual statement setting forth payments, earnings, value, and other specified information; (3) impose a penalty on employers who fail to provide eligible employees access to an automatic IRA arrangement; (4) allow employers who do not have more than 100 employees a tax credit for costs associated with establishing an automatic IRA arrangement; and (5) increase the dollar limitation on the tax credit for small employer pension plan startup costs.

Establishes an Automatic IRA Advisory Group to make recommendations regarding automatic IRA investment options.

Requires the Secretary and the Secretary of Labor to jointly conduct feasibility studies on: (1) extending spousal consent requirements to automatic IRA arrangements; (2) automatically transferring amounts saved by employees in retirement bonds into alternative, private sector, diversified investments when employees' automatic IRA balances reach a certain dollar level; (3) using investment data to notify individuals with multiple small balance retirement accounts of consolidation options; and (4) using investment arrangements associated with automatic IRAs to assist in addressing the problem of abandoned accounts.

Directs the Secretaries to prescribe administrative guidance for the use of multiple employer plans by December 31, 2015.