IRS Publication 938 Guide: REMIC & CDO Tax Reporting Rules

Introduction: What is Publication 938?

IRS Publication 938, officially titled Real Estate Mortgage Investment Conduit (REMIC) Reporting Information (And Other Collateralized Debt Obligations (CDOs)), is the federal government’s primary administrative directory for mortgage securitizations. The mortgage-backed securities market is one of the largest financial sectors in the world, allowing thousands of individual home and commercial loans to be bundled into investment pools and sold to investors as bonds.

To govern these complex financial pools, Congress created Real Estate Mortgage Investment Conduits (REMICs) under the Tax Reform Act of 1986. While REMICs are generally pass-through entities that pay no corporate income tax, the tax reporting required for their investors is highly complex. Publication 938 serves as an official master directory that provides the names, addresses, phone numbers, and CUSIP identifiers of the designated representatives for every registered REMIC and CDO in the United States.

The primary purpose of Publication 938 is to bridge the information gap between the master mortgage pool and the financial middlemen—such as brokerage firms, banks, and nominee custodians—who hold these bonds in street name for clients. By publishing this directory, the IRS ensures that brokers can obtain the precise financial data needed to report interest and Original Issue Discount (OID) to investors on their annual tax forms.

Who Should Read This Publication?

Publication 938 is primarily an institutional reference manual designed for financial intermediaries, tax preparers, and structured finance professionals:

• Brokerage Firms and Banks: Financial institutions acting as nominees or custodians that hold REMIC regular interests or CDOs on behalf of client accounts.
• Back-Office Tax Operations: Operations teams responsible for calculating and generating annual Form 1099-INT and Form 1099-OID statements for bondholders.
• REMIC and CDO Issuers: Financial entities, trustees, and loan servicers required to submit initial registration data and field information requests from nominees.
• Institutional and Advanced Investors: Sophisticated bondholders holding regular or residual interests who need to verify tax reporting contacts.
• CPAs and Structured Finance Auditors: Accounting professionals reviewing pass-through income allocations and verifying OID accrual schedules.

Key Topics Covered

Publication 938 organizes complex structured finance tax rules into practical, directory-focused chapters. Its core topics include:

• The Legal Structure of REMICs and CDOs: How mortgage pools function as tax-exempt pass-through vehicles under Sections 860A through 860G.
• Regular vs. Residual Interests: The tax distinctions between debt-like regular securities and equity-like residual pass-through shares.
• The Master Directory: Contact information, CUSIP numbers, and startup dates for active REMIC trusts and CDO offerings.
• Original Issue Discount (OID) Calculation Rules: How fluctuating mortgage prepayment speeds alter annual taxable interest accruals.
• The Role of Form 8811: The mandatory registration form filed by issuers that powers the Publication 938 directory.
• Nominee Information Deadlines: Strict timelines governing how quickly issuers must provide tax data to inquiring brokers.

Detailed Breakdown of Main Concepts

1. What Are REMICs and CDOs?

A Real Estate Mortgage Investment Conduit (REMIC) is an investment vehicle formed specifically to hold a fixed pool of mortgages secured by real property. A Collateralized Debt Obligation (CDO) is a broader category of structured debt security backed by a pool of various loans, bonds, or other financial receivables.

Under federal tax law, a REMIC is not treated as an independent taxable corporation. Provided it meets strict statutory asset tests and distributes its earnings, the REMIC pays zero federal income tax. Instead, the income is passed through to the investors who hold ownership interests in the conduit, ensuring that the mortgage pool avoids double taxation.

2. Regular Interests vs. Residual Interests

Publication 938 explains that a REMIC issues two completely different classes of securities, each governed by separate tax rules:

• Regular Interests: These are structured like standard bonds. They have fixed principal amounts and specified interest rates. For tax purposes, regular interests are treated strictly as debt instruments. Holders report interest and Original Issue Discount as ordinary income, regardless of whether they normally use the cash or accrual accounting method.
• Residual Interests: A REMIC can have only one class of residual interest, which represents the remaining equity or ownership in the mortgage pool. Residual holders report their daily share of the REMIC’s taxable income or net loss on Schedule Q of Form 1066. This includes “excess inclusions,” which are statutory phantom income items that cannot be offset by personal deductions or net operating losses.

3. The Nominee Problem and Why Publication 938 Exists

The vast majority of everyday investors who purchase mortgage-backed securities do not hold paper certificates issued directly by the REMIC. Instead, the securities are held in “street name” inside custodial brokerage accounts at firms like Fidelity, Charles Schwab, or Vanguard. The brokerage is legally classified as a “nominee.”

Federal law requires the nominee broker to mail Form 1099-INT and Form 1099-OID to the investor each January. However, calculating the exact amount of taxable interest and OID on a pool of thousands of mortgages is mathematically impossible for a retail broker because homeowners pay off mortgages at unpredictable speeds. Publication 938 provides the official directory of REMIC contact representatives so brokers know exactly whom to contact to obtain the necessary tax calculation figures.

4. Form 8811: The Source of Publication 938

Publication 938 is not created out of thin air; it is generated directly from mandatory government filings. Under Treasury regulations, when a new REMIC or CDO is established, the trustee or issuer must file Form 8811 (Information Return for Real Estate Mortgage Investment Conduits and Issuers of CDOs) within 30 days of the startup date.

Form 8811 provides the IRS with the entity’s name, employer identification number, startup date, CUSIP numbers for each class of securities, and the name, title, address, and telephone number of the official tax representative. The IRS compiles this information and continuously updates the Publication 938 directory on the official IRS website.

5. Original Issue Discount (OID) Mechanics

Mortgage-backed securities are frequently issued at a discount—meaning the original purchase price is lower than the stated face value at maturity. This discount is known as Original Issue Discount (OID) and is treated by the IRS as a form of interest.

Under federal tax rules, OID cannot simply be reported when the bond matures decades later. It must be accrued and reported as taxable income each year over the life of the instrument. Because mortgage pools experience changing prepayment speeds as interest rates rise and fall, the REMIC representative must calculate these OID adjustments using specialized financial models, which are then passed to brokers using the Publication 938 directory.

6. Mandatory Response Timelines for Issuers

Publication 938 establishes strict administrative timelines under federal regulations. When a broker, nominee, or investor identifies a REMIC representative in the directory and submits a written request for tax information, the representative cannot delay.

The designated representative is required by federal law to furnish the necessary tax information—including quarterly interest accruals, OID factors, and market discount figures—within 30 calendar days of receiving the request. This ensures that brokerage firms have enough time to assemble and mail accurate Form 1099 statements to retail investors before annual filing deadlines.

Practical Examples and Scenarios

The following examples illustrate how financial institutions and issuers apply the directory rules outlined in Publication 938.

Scenario 1: Brokerage Filing Year-End Form 1099-OID

A regional brokerage firm holds $2,000,000 worth of residential mortgage regular interest bonds in street name for forty retired clients. As tax season approaches, the brokerage’s tax department must report the correct OID accrual on each client’s Form 1099-OID.

Because the bond’s underlying mortgages experienced rapid refinancing prepayments during the year, the standard OID schedule must be adjusted. The brokerage tax team accesses Publication 938 on IRS.gov, searches the security’s CUSIP number, and identifies the designated REMIC representative. The broker submits an information request, receives the verified quarterly OID figures within 30 days, and successfully issues accurate tax statements to its clients.

Scenario 2: Launching a New Commercial Mortgage Securitization

An investment banking group pools $400 million in commercial warehouse mortgages into a newly created REMIC trust on March 15. The trust issues multiple classes of regular bonds and a single class of residual equity.

Under Publication 938 regulations, the trustee must file Form 8811 with the IRS within 30 days of the March 15 startup date. The trustee submits the form detailing the master representative’s office and all assigned CUSIP numbers. The IRS processes the filing and includes the new trust in the Publication 938 database, ensuring that any custodian or dealer trading the bonds can locate the proper tax contact.

REMIC Regular vs. Residual Interests Comparison

Characteristic	Regular Interest	Residual Interest
Legal Character	Treated as a debt instrument (Bond)	Treated as equity ownership (Pass-Through)
Taxable Income Sourcing	Fixed interest and Original Issue Discount	Distributive share of daily taxable net profit or loss
Annual Reporting Form	Form 1099-INT and Form 1099-OID	Schedule Q (Form 1066)
Accounting Method Rule	Must use accrual method for reporting	Reports daily accruals regardless of method
Excess Inclusions	Not applicable	Cannot be offset by personal deductions or NOLs

How This Publication Relates to Specific Forms

Publication 938 acts as an administrative directory coordinating several critical structured finance tax documents:

• Form 8811 (Information Return for REMICs and Issuers of CDOs): The foundational input form filed by trustees to provide the CUSIP numbers and representative contact details published in Publication 938.
• Form 1066 (U.S. Real Estate Mortgage Investment Conduit Income Tax Return): The annual tax return filed by the REMIC entity itself to report master portfolio income and deductions.
• Schedule Q (Form 1066): The quarterly statement issued by the REMIC to residual interest holders reporting their allocated share of income, losses, and excess inclusions.
• Form 1099-OID & Form 1099-INT: The standard information statements furnished to regular interest holders by brokerage nominees using the contact details found in Publication 938.
• Schedule B & Schedule E (Form 1040): Where individual taxpayers report regular interest (Schedule B) or residual pass-through income (Schedule E).

Common Misunderstandings Clarified

Misunderstanding 1: “Publication 938 is an instruction guide for individual tax returns.”

Publication 938 is not an instructional filing guide for everyday taxpayers. It does not contain tax tables or individual deductions. It is an institutional directory and regulatory compliance handbook designed primarily for financial middlemen, brokerages, and corporate issuers.

Misunderstanding 2: “Retail investors must download Publication 938 to report bond income.”

Everyday investors holding mortgage bonds or mutual funds do not need to read Publication 938. Your brokerage firm or custodian uses Publication 938 behind the scenes to gather the necessary data. As an individual investor, you simply report the numbers printed on your annual Form 1099-OID or Schedule Q.

Misunderstanding 3: “REMIC trusts pay corporate taxes on their mortgage interest.”

A REMIC is a statutory pass-through vehicle that is completely exempt from federal income taxation at the entity level. The only taxes a REMIC might pay are penalty taxes on prohibited transactions (such as trading loans improperly) or contributions received after startup.

Misunderstanding 4: “Original Issue Discount is only taxed when the bond is redeemed.”

Many investors assume that buying a bond at a discount means paying tax on the profit when the bond matures. Under federal OID rules, the discount represents phantom interest that must be accrued, reported, and taxed annually over the life of the bond, even before principal cash is received.

Why This Publication Matters for Taxpayers & Markets

In a financial ecosystem containing trillions of dollars in securitized home mortgages, accurate tax reporting is a massive undertaking. Without Publication 938, brokerage firms holding bonds for millions of clients would have no centralized, standardized method for tracking down the specific accountants and trustees responsible for calculating complex prepayment adjustments.

By establishing clear lines of communication between mortgage trusts and financial intermediaries, Publication 938 ensures that Forms 1099 are issued accurately and on time. This prevents automated IRS matching discrepancies, shields brokerages from information reporting penalties, and ensures individual investors receive verified, audit-proof tax data.

Frequently Asked Questions

How often is Publication 938 updated by the IRS?

Historically printed as a quarterly or annual booklet, Publication 938 is maintained today as a continuously updated electronic directory on the official IRS website. The online database updates regularly as new entities file Form 8811.

What is an ‘excess inclusion’ on a REMIC residual interest?

An excess inclusion is a specialized component of a REMIC residual interest’s taxable income that represents phantom income generated by timing differences in the mortgage pool. Under federal law, an excess inclusion can never be offset by personal deductions or net operating losses, and is fully taxable even to tax-exempt entities.

What happens if a newly formed REMIC fails to file Form 8811?

Failing to file Form 8811 within 30 days of the startup date violates federal Treasury regulations. The issuer can be subjected to civil reporting penalties, and the entity will be omitted from Publication 938, preventing brokerage firms from obtaining timely tax data for investors.

How does a broker use Publication 938 to obtain tax data?

A broker locates the security’s CUSIP number in the Publication 938 database, which lists the designated representative’s contact information. The broker submits a formal written inquiry, and the representative must provide the quarterly OID and interest figures within 30 calendar days.

Can a foreign investor purchase REMIC regular interests?

Yes. Interest and Original Issue Discount paid to a nonresident alien or foreign corporation holding a REMIC regular interest generally qualify for the portfolio interest exemption, meaning the income is exempt from standard 30% U.S. withholding tax, provided proper Form W-8 documentation is maintained.

Conclusion

IRS Publication 938 is an indispensable administrative pillar supporting the United States mortgage securitization market. By serving as the central clearinghouse for REMIC and CDO representative information, it bridges the gap between complex multi-billion-dollar mortgage trusts and the retail brokerage firms that serve everyday investors.

Understanding the distinction between regular and residual interests, complying with Form 8811 registration mandates, and following strict nominee disclosure timelines ensures that mortgage-backed securities function smoothly. For financial institutions and structured finance professionals, Publication 938 provides the operational certainty required to keep the nation’s mortgage investment market transparent, accurate, and fully compliant with federal tax law.