Exhibit 10.3

EXECUTION COPY

RESPONSE TO
NOTICE INCREASE REQUEST

May 30, 2014

SunTrust Bank

303 Peachtree Street, N. E.

Atlanta, Georgia 30308

Attention: Robert Ashcom

Telecopy Number: (404) 581-1775

Re: TPG Specialty Lending,
Inc. (the Company)

Ladies and Gentlemen:

We refer to (a) that certain Second Amended and Restated Senior Secured Revolving Credit Agreement, dated as February 27, 2014 (as
amended, supplemented, amended and restated, or otherwise modified from time to time, the Credit Agreement; capitalized terms used in this response and not otherwise defined have the meanings for such terms set forth in the Credit
Agreement), by and among the Company, the Lenders from time to time party thereto and SunTrust Bank, as Administrative Agent (in such capacity, the Administrative Agent); and (b) the Notice of Commitment Increase Request,
dated as of May 28, 2014, provided by the Company to the Administrative Agent (the Notice).

Pursuant to the Notice and
Section 2.08(e) of the Credit Agreement, we deliver this response (this Response Letter) to confirm that each of the Company and [        ] (the Assuming Lender)
agrees that, effective upon the satisfaction of the conditions set forth in Sections 2.08(e)(i) and (ii) of the Credit Agreement, the Assuming Lender shall assume a Multicurrency Commitment under the Credit Agreement equal to
[          ] and shall for all purposes be deemed a Multicurrency Lender under the Credit Agreement and any other documents or instruments delivered pursuant thereto.

This Response Letter shall be binding upon, and inure to the benefit of, the parties hereto and their respective successors and assigns. This
Response Letter may be executed in any number of counterparts, which together shall constitute one instrument. Delivery of an executed counterpart of a signature page of this Response Letter by telecopy, email, or other electronic method of
transmission shall be effective as delivery of a manually executed counterpart of this Response Letter. This Response Letter shall be governed by, and construed in accordance with, the laws of the State of New York.



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Very truly yours,CITY NATIONAL BANKBy:

/s/ Brandon L. Feitelson, C.F.A.Name:

Brandon L. Feitelson, C.F.A.Title:

Senior Vice PresidentTPG SPECIALTY LENDING, INC.By:

/s/ Alan KirshenbaumName:

Alan KirshenbaumTitle:

Chief Financial Officer




|                                                        |  |                 
|------------------------------------------------------- |  | ----------------
|ACKNOWLEDGED, ACCEPTED AND
AGREED:                     
|                                                       
|SUNTRUST BANK, as
Administrative Agent and Issuing Bank
|                                                        | 
|By:                                                     |  | /s/ Doug Kennedy
|Name:                                                   |  | Doug Kennedy    
|Title:                                                  |  | Vice President  



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COMERICA BANKBy:

/s/ Timothy ORourkeName:

Timothy ORourkeTitle:

Vice PresidentTPG SPECIALTY LENDING, INC.By:

/s/ Alan KirshenbaumName:

Alan KirshenbaumTitle:

Chief Financial Officer




|                                                        |  |                 
|------------------------------------------------------- |  | ----------------
|ACKNOWLEDGED, ACCEPTED AND
AGREED:                     
|                                                       
|SUNTRUST BANK, as
Administrative Agent and Issuing Bank
|                                                        | 
|By:                                                     |  | /s/ Doug Kennedy
|Name:                                                   |  | Doug Kennedy    
|Title:                                                  |  | Vice President  



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HSBC BANK USA, NATIONAL
ASSOCIATIONBy:

/s/ Edwin SoogrimName:

Edwin SoogrimTitle:

Vice PresidentTPG SPECIALTY LENDING, INC.By:

/s/ Alan KirshenbaumName:

Alan KirshenbaumTitle:

Chief Financial Officer




|                                                        |  |                 
|------------------------------------------------------- |  | ----------------
|ACKNOWLEDGED, ACCEPTED AND
AGREED:                     
|                                                       
|SUNTRUST BANK, as
Administrative Agent and Issuing Bank
|                                                        | 
|By:                                                     |  | /s/ Doug Kennedy
|Name:                                                   |  | Doug Kennedy    
|Title:                                                  |  | Vice President  



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MIZUHO BANK, LTD.By:

/s/ James R. FayenName:

James R. FayenTitle:

Deputy General ManagerTPG SPECIALTY LENDING, INC.By:

/s/ Alan KirshenbaumName:

Alan KirshenbaumTitle:

Chief Financial Officer




|                                                        |  |                 
|------------------------------------------------------- |  | ----------------
|ACKNOWLEDGED, ACCEPTED AND
AGREED:                     
|                                                       
|SUNTRUST BANK, as
Administrative Agent and Issuing Bank
|                                                        | 
|By:                                                     |  | /s/ Doug Kennedy
|Name:                                                   |  | Doug Kennedy    
|Title:                                                  |  | Vice President  



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PATRIOT BANKBy:

/s/ Bill HolbertName:

Bill HolbertTitle:

Senior Vice PresidentTPG SPECIALTY LENDING, INC.By:

/s/ Alan KirshenbaumName:

Alan KirshenbaumTitle:

Chief Financial Officer




|                                                        |  |                 
|------------------------------------------------------- |  | ----------------
|ACKNOWLEDGED, ACCEPTED AND
AGREED:                     
|                                                       
|SUNTRUST BANK, as
Administrative Agent and Issuing Bank
|                                                        | 
|By:                                                     |  | /s/ Doug Kennedy
|Name:                                                   |  | Doug Kennedy    
|Title:                                                  |  | Vice President  



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SANTANDER BANK, N.A.By:

/s/ Gilbert TorresName:

Gilbert TorresTitle:

Senior Vice PresidentTPG SPECIALTY LENDING, INC.By:

/s/ Alan KirshenbaumName:

Alan KirshenbaumTitle:

Chief Financial Officer




|                                                        |  |                 
|------------------------------------------------------- |  | ----------------
|ACKNOWLEDGED, ACCEPTED AND
AGREED:                     
|                                                       
|SUNTRUST BANK, as
Administrative Agent and Issuing Bank
|                                                        | 
|By:                                                     |  | /s/ Doug Kennedy
|Name:                                                   |  | Doug Kennedy    
|Title:                                                  |  | Vice President