Exhibit 99.1

Interpath (Ireland) Limited Riverside Two Sir John Rogerson’s Quay Dublin 2 D02 KV60 Ireland

Private & confidential

The Directors

GS Mortgage-Backed Securities Trust 2026-Irpm1 DAC

3rd Floor,

Waterloo Exchange,

Dublin 4,

D04 E5W7

Ireland

Penryn Funding 2024 DAC

1-2 Victoria Buildings,

Haddington Road,

Dublin 4

D04 XN32

Ireland

Goldman Sachs International

Plumtree Court,

25 Shoe Lane,

London,

United Kingdom,

EC4A 4AU

29 June 2026

Dear All,

Project Falcon

The terms of the engagement letter agreed between us and dated 24 June 2026 (the “Engagement Letter”) are deemed to have been incorporated in this final report (also referred to as the Deliverable) and governs the matters addressed by this report and its use, but certain terms of the Engagement Letter are amended by the terms of this report to the extent expressly set out herein.

We have performed certain agreed procedures in relation to the portfolio of Irish mortgage loans proposed to be the subject of a securitisation (the “Securitisation”). Attached to this Deliverable are the Description of Services, attached as Appendix 1, Details of our Findings, as Appendix 2, Summary Tables, as Appendix 3 and the Loan Level Findings Report, as Appendix 4.

Interpath (Ireland) Limited is a limited company registered in Ireland (trading as “Interpath Advisory”). It’s parent is Interpath Ltd which a limited company registered in Engalnd and Wales. Interpath Ltd is authorised and regulated by the Financial Conduct Authority under FCA registration number 951782.

Registered in Ireland 713472.

Registered office: 70 Sir John Rogerson’s Quay, Dublin 2.

This report is addressed to GS Mortgage-Backed Securities Trust 2026-Irpm1 DAC (the “Issuer”), Penryn Funding 2024 DAC (the “Seller”), and Goldman Sachs International (the “Arranger” and “Lead Manager”).

The procedures that we have performed are solely for the purpose of assisting you in determining the accuracy of underwriting procedures that have been performed in connection with the Securitisation and so may not be suitable for any other purpose. We will not accept any responsibility to any other party to whom our Deliverable is shown or into whose hands it may come.

Procedures

The procedures performed were not intended to satisfy any criteria for due diligence published by any nationally recognised statistical rating organisation (“NRSRO”).

Between the dates of 31 March 2026 and 24 June 2026 (the “Review Period”), we have been provided by the Seller with a daily list of account numbers for newly originated Irish mortgage loans originated by Nua Money Limited (the “Originator”). 700 of these mortgage loans, with an aggregated original balance of €194,134,149 have subsequently been purchased by the Seller during the Review Period, and are proposed to be the subject of the Securitisation (the “Portfolio”).

The procedures were performed through access to information held within the loan management system of the Originator (the “Source Material”), made available to us by the Originator via remote access.

We have not verified or evaluated such Source Material and therefore we express no opinion or any other form of assurance regarding the reliability, accuracy or adequacy of the Source Material, or as to whether any of the Source Material omit any material facts. Furthermore, we express no opinion or any other form of assurance regarding the reliability, accuracy or adequacy of the disclosures in the Source Material, or any legal matters relating to the Portfolio, or the physical existence of the underlying security.

The procedures performed did not address, without limitation: (i) the value of any collateral securing the Portfolio, (ii) the compliance of the Originator of the Portfolio with applicable laws and regulations, or (iii) any other factor or characteristic of the Portfolio that would be material to the likelihood that the issuer or the asset-backed security will pay interest and principal in accordance with applicable terms and conditions.

The procedures performed may not address all of the items of interest to a user of the report and may not meet the needs of all users of the report and, as such, users are responsible for determining whether the procedures performed are appropriate for their purposes. The appropriateness of these procedures is solely the responsibility of the addressees of this report. No other party acknowledged the appropriateness of the procedures. Consequently, we make no representations regarding the appropriateness of the procedures described herein.

Findings

Details of the findings, summary tables and loan level findings found as a result of performing the agreed procedures are listed in Appendix 2, Appendix 3 and Appendix 4.

General

This report may only be relied upon in respect of the matters to which it refers and as of its date. In relying upon this report, you agree (save as otherwise expressly agreed in the Engagement Letter) that we have no responsibility to and we will not perform any work subsequent to the date of this report nor to consider, monitor, communicate or report any events or circumstances which may occur or may come to light subsequent to the date of this report. This report is issued for your benefit only and may not be used or relied upon by any third party without our express written consent.

This Deliverable is not issued in accordance with the professional standards of the American Institute of Certified Public Accountants or the US Public Company Accounting Oversight Board. We will provide separately an executed Form ABS Due Diligence-15E, Certification of Provider of Third-Party Due Diligence Services for Asset-Backed Securities (“Form ABS Due Diligence-15E”), using the form made available by the US Securities and Exchange Commission (“SEC”), to which this Deliverable will be appended. The executed Form ABS Due Diligence-15E will be provided, without in any way or on any basis affecting or adding to or extending our duties and responsibilities to you or giving rise to any duty or responsibility being accepted or assumed by or imposed on Interpath to any party except you, to facilitate your compliance with SEC Release No. 34-72936, Nationally Recognized Statistical Rating Organizations (the “SEC Release”), pursuant to which you are required to make publicly available the findings and conclusions of any third-party due diligence report obtained.

The requirement to make publicly available findings and conclusions includes disclosure of the criteria against which loans were evaluated, and how the evaluated loans compared to those criteria, along with the basis for including any loans not meeting those criteria. This is accomplished by including such information, which will include this Deliverable, in Form ABS-15G, Asset-Backed Securitizer Report Pursuant to Section 15G of the Securities Exchange Act of 1934 (“Form ABS 15G”), which is required to be furnished by the issuer or underwriter to the SEC through the Electronic Data Gathering, Analysis, and Retrieval (“EDGAR”) system.

The issuer, sponsor or underwriter of an asset–backed securitisation is required to maintain a website (the “Rule 17g-5 website”) pursuant to paragraph (a)(3) of Rule 17g-5 of the US Code of Federal Regulations (17 CFR 240.17g-5). The SEC Release requires any NRSRO producing a credit rating to which “third party due diligence services” relate, to publish with its rating any executed Form ABS Due Diligence-15E containing information about the relevant security or money market instrument that the NRSRO receives or obtains through a Rule 17g-5 website. The agreed procedures performed by Interpath on which this Deliverable reports amount to “third party due diligence services” as defined in the SEC Release.

To facilitate a relevant NRSRO meeting this publication obligation, we are required to furnish any executed Form ABS Due Diligence-15E to any such NRSRO. As envisaged by the SEC Release, we will do so by providing the prescribed form to the issuer, sponsor, or underwriter of the securitisation that maintains the Rule 17g-5 website, or to any NRSRO that requests it. In addition, the SEC Release requires that an NRSRO producing a credit rating publicly disclose each prescribed form that was posted to the Rule 17g-5 website. Such information may therefore be posted on the website of any relevant NRSRO.

Any such publicity shall take place, without in any way or on any basis affecting or adding to or extending our duties and responsibilities to you or giving rise to any duty or responsibility being accepted or assumed by or imposed on Interpath to any party except you, to facilitate your compliance with the SEC Release. Accordingly, any party (including rating agencies and investors) obtaining access to this Deliverable as appended to the executed Form ABS Due Diligence-15E or separately is not authorised by Interpath to use or rely upon the Deliverable, any such use or reliance shall take place at the relevant party’s own risk and, to the fullest extent permitted by law, we will have no responsibility and will deny any liability to any such party.

Attached:

Appendix 1

Description of Services

Procedures

The procedures that the Seller has instructed us, and that we have agreed, to perform are set out below.

Data Integrity;

For all loans in the Portfolio, we will tie up the following data fields to the loan application and/or system of record:

File Completeness;

For all loans in the Portfolio, we will check that the loan file includes relevant loan documents, including (where applicable):

Eligibility Criteria/Underwriting;

For all loans in the Portfolio, we will:

Cash Reconciliation;

For all loans in the Portfolio, we will:

Appendix 2

Details of the Findings

Methodology

The agreed procedures were designed by the Seller to assess the completeness of loan documentation, adherence to underwriting and operational procedures, borrower eligibility, data integrity, and compliance with additional warehouse eligibility requirements of newly originated Irish mortgage loans originated by the Originator.

The procedures were performed by reference to the Originator's approved underwriting procedures, credit policy, operational procedures and AML/KYC framework. These policies and procedures have been established by the Originator to support compliance with the regulatory requirements applicable to Irish residential mortgage lending, including applicable requirements of the Central Bank of Ireland and relevant Irish legislation. Accordingly, the agreed procedures focused on confirming adherence to the Originator's documented policies and procedures and did not constitute an independent legal or regulatory compliance review.

Interpath reviewed 100% of the Irish mortgage loans submitted by the Originator for consideration under the warehouse funding process during the Review Period and no sampling methodologies were applied.

Interpath was provided with the relevant underwriting policies, credit policies, operational procedures and supporting guidance documentation to facilitate the review. In addition, the Originator provided Interpath with daily SEPA payment instruction files in XML format, which were utilised as an independent source for the validation of key loan information and disbursement details.

Interpath identified documentation queries, data discrepancies and requests for clarification which were referred to the Originator for resolution.

Procedures

The agreed procedures were as follows:

Confirm the documents and underwriting decisions are in accordance with the Underwriting procedures and Credit policy

This included borrower characteristics, repayment capacity, loan purpose, loan-to-value ratios, property information, income verification and affordability assessments. Interpath verified that key underwriting steps had been met in line with required policies. There were no exceptions.

Confirm the credit underwriting process has been followed including evidence that full KYC and AML checks have been completed

This included credit searches, affordability assessments, income and expenditure analysis, identity verification, address verification and sanctions screening. Interpath verified that key KYC and AML steps had been met in line with required policies. There were no exceptions.

The borrower has accepted the terms of the loan agreement

This included confirmation of the presence of executed loan documentation, borrower acceptance records maintained within the Originator's systems and additional documentation required to evidence acceptance of the lending terms. There were no exceptions.

Check each loan meets any additional warehouse eligibility criteria

This included loan characteristics, borrower eligibility criteria, property requirements, documentary completeness and transaction-specific eligibility conditions. Interpath verified that key warehouse eligibility criteria had been met. There were no exceptions.

DI Check- Confirm no data integrity differences

This included verification, where applicable, of the following fields:

There were no exceptions.

Application Form

This included borrower details, loan purpose, property information, employment details, income disclosures and other relevant application data. Interpath verified that key information recorded within the mortgage loan file was complete and consistent with the information used during the underwriting process. There were no exceptions.

Signed Declarations

This included confirmation of the presence of borrower declarations and verified that such declarations had been executed and retained within the mortgage loan file. There were no exceptions.

Credit Report

This included credit reports and associated credit information available within the Originator's platform for each mortgage loan, including borrower credit data sourced from the Central Credit Register. Interpath verified that the application had been assessed in accordance with key underwriting steps and credit policy. There were no exceptions.

KYC/AML documentation

This included confirmation of identity verification, proof of address documentation and additional documentation required under applicable KYC and AML procedures. There were no exceptions.

Valuation Report

This included verifying consistency between the valuation amount recorded within the Originator's systems and the supporting valuation documentation. Interpath also confirmed that the valuation was completed within the required timeframe, related to a principal dwelling house, was prepared by a qualified valuer, included comparable property evidence, and did not identify any material concerns affecting the suitability of the property as security for the mortgage loan. There were no exceptions.

Evidence of affordability

This included confirming that evidence supporting the affordability assessment was present within the file, that the figures used in the affordability analysis could be traced back to supporting documentation and were calculated in accordance with the Originator's policy requirements. Interpath verified that the resulting affordability metrics met key underwriting criteria and lending thresholds. There were no exceptions.

Independent legal advice declaration

This included confirming the presence of a signed independent legal advice declaration, where applicable. Interpath verified that the declaration had been executed in accordance with the Originator's requirements. There were no exceptions.

Signed Solicitors Undertaking re Title, Mortgage agreement & Subsequent Registration

This included confirming the presence of the Law Society of Ireland approved form of Residential Mortgage Lending Solicitor's Undertaking within each mortgage loan file. Interpath verified that the undertaking had been completed and executed. There were no exceptions.

Disbursement Confirmed To Bank Account Matches Borrower Solicitor

This included comparing the disbursement details recorded within the mortgage loan application against the daily SEPA payment instruction files to confirm that loan proceeds were being remitted to the borrower solicitor's bank account as recorded in the supporting Solicitors Undertaking. There were no exceptions.

Appendix 3

Summary Tables

Appendix 4

Loan Level Findings Report

Appendix 4 - Loan Level Findings Report