Shrinking Emergency Account Losses Act of 2017 or the SEAL Act This bill amends the Internal Revenue Code, with respect to loans made from a qualified employer plan, to: (1) extend the period for repayment of loans if a plan terminates or a plan participant becomes unemployed, and (2) prohibit qualified employer plans from making loans using credit cards or any other similar arrangement. The bill also requires the Department of the Treasury to modify regulations governing hardship distributions from qualified employer plans to allow participants to make additional contributions to a plan during the six-month period following a hardship distribution.