Exhibit 31.3

CERTIFICATION

I, David W. Nelms, certify that:

1. I have reviewed this Amendment No. 1 to the Annual Report on Form 10-K of Discover Financial Services; and

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report.

Date: February 25, 2016

/s/ DAVID W. NELMS

David W. Nelms

Chairman of the Board and

Chief Executive Officer