Tax-Exempt Advance Refunding and U.S. Airports: The Eight-Year Cost of Prohibition

Changelog

Introduction: The Prohibition and Its Eight-Year Cost

Tax-exempt advance refunding was a debt management tool that allowed U.S. airports and other public entities to issue new bonds years before old bonds matured, locking in lower interest rates when markets moved favorably. The tool was legal and widely used. On a $100 million bond issuance with a 150 basis point rate move, airports captured $2–$5 million in present-value savings. This directly reduced debt service costs, which flowed through to lower airline fees and ultimately lower ticket prices.

That tool no longer exists. The Tax Cuts and Jobs Act of 2017 (Pub. L. 115–97), signed December 22, 2017, and January 1, 2018, eliminated tax-exempt advance refunding entirely. Only current refunding—issuing new bonds within 90 days of the old bonds' call or maturity date—is now permitted under IRC §149(d). In the 90-day window, rate moves typically range from −20 to +40 basis points (U.S. Treasury yield curve data, 2010–2025), and airports capture savings of 5–15 basis points instead of the 80–150 basis points previously available (per MSRB refunding data, 2010–2017 vs. 2018–2025).

The prohibition carries an estimated $17.3 billion ten-year federal revenue impact. The Joint Committee on Taxation estimated the prohibition would raise $17.3 billion in federal tax revenue over ten years (2018–2027) by suppressing municipal bond issuance and tax-exemption benefits. Meanwhile, the Brookings Institution estimated in 2023 that the nationwide prohibition costs public issuers (schools, hospitals, municipalities, airports, transit systems) approximately $495 million per year in foregone refinancing savings. Airports represent approximately 12–15% of municipal bond refunding activity (per MSRB 2024 data and EMMA filings), suggesting an airport-specific annual cost of $300–$400 million nationally.

Over the eight years since enactment (2018–2025), airports collectively have foregone an estimated $2.4–$3.2 billion in present-value refinancing savings (calculated as $300–$400 million annually × 8 years, undiscounted)—capital that could have been deployed toward terminal improvements, equipment modernization, or reduced aeronautical rates. This article examines the statutory framework, the economics of advance and current refunding, the workarounds airports now use, the legislative landscape, and the strategic implications for airport finance teams. The intended audience is airport CFOs, finance directors, bond counsel, and institutional investors managing or holding airport bonds.

The Statutory Prohibition: TCJA 2017

TCJA 2017: The Original Prohibition

The Tax Cuts and Jobs Act of 2017 (Pub. L. 115–97), signed December 22, 2017, added a new restriction to IRC §149(d), the governing statute for tax-exempt bonds. The operative language reads:

"Tax-exempt advance refunding bonds are prohibited. An obligation is not described in subsection (a) if it is issued as part of an issue any portion of which is to be used to refund another obligation unless such refunding is a current refunding. A refunding shall be treated as a current refunding when (A) the refunded issue is retired within 90 days after issuance of the refunding issue, and (B) the first redemption of the refunded issue is not later than the date of issuance of the refunding issue."

This language codified an absolute prohibition. Prior to 2017, IRC §149 permitted advance refunding without time limitation. The practice was widespread: approximately 37–42% of long-term municipal bond volume in 2010–2017 consisted of refundings (MSRB Annual Report 2017), with a portion being advance refundings. The Joint Committee on Taxation estimated that eliminating advance refunding would raise $17.3 billion in federal tax revenue over the ten-year budget window (2018–2027).

The revenue-raising logic is straightforward: without advance refunding, public entities may hold bonds outstanding longer, which delays the opportunity to refinance at lower rates. This extends the period during which higher coupons are paid, suppresses the volume of new bond issuance, reduces the aggregate value of the tax-exemption subsidy, and generates higher federal tax revenue. The U.S. Treasury and IRS do not publish the tax-exemption cost separately, but CBO and CRS analyses confirm it remains one of the largest tax expenditures in the federal budget.

Legislative Status: Pending Advance Refunding Act

Since the TCJA 2017 prohibition, airport finance leaders, the American Association of Airport Executives (AAAE), and institutional investors have sought restoration of the advance refunding tool. However, no legislation has passed to date.

The Advance Refunding Act (H.R. 2780 and S. 1306, 118th Congress), reintroduced in multiple Congressional sessions, would restore the tool and explicitly exempt advance refunding from the IRC §149(d) prohibition. However, it has not passed either chamber. The primary barrier is the $17.3 billion revenue-loss offset requirement: under budget rules, any bill restoring advance refunding must offset the lost federal revenue by raising taxes elsewhere or cutting federal spending. The bill has not reached markup in committee in the 118th Congress (2023–2024).

How Advance Refunding Worked: Credit Mechanics and Market Conditions (2000–2017)

Credit Substitution and Certainty

Advance refunding operated on a principle of trust—the substitution of credit exposure. Before the prohibition, the mechanics were straightforward:

Step 1: Market Opportunity. An airport issued bonds at a prevailing market rate. For example, in 2010, it issued $100 million of 30-year bonds callable in 10 years at a 5.0% coupon.

Step 2: New Bond Issuance and Defeasance. Two years later, in 2012, when interest rates declined by approximately 150 basis points (similar A-rated credits issued at 3.5%), the airport issued new bonds at 3.5%, borrowing $100 million (plus transaction costs). key, the proceeds were not used for operations. Instead, they were immediately invested in U.S. Treasury SLGS (State and Local Government Series bonds) or high-grade municipal securities maturing on the original bonds' call date (in this example, 2020). This is the process of defeasance under GASB (Governmental Accounting Standards Board) accounting standards.

Step 3: Irrevocable Escrow Account. The Treasury securities were held in an irrevocable escrow account, dedicated solely to paying principal and interest on the old 5.0% bonds when they were called. The IRC §149 permitted this structure because it met the "in-substance defeasance" test: the old bonds were economically satisfied, removed from the airport's balance sheet, and no longer exposed airport credit to investors.

Step 4: Savings Realization. The airport captured the spread: 5.0% (old bonds) − 3.5% (new bonds) = 1.5% annual savings. On $100 million, that spread generated approximately $2–$5 million in present-value savings over the remaining 10-year period. The old bonds still traded; investors understood they were backed by Treasury securities, not airport credit. Both bonds remained outstanding until the old bonds matured or were called. From the airport's perspective, it had borrowed at both rates but would service only the lower rate—a genuine economic gain.

This is the credit substitution mechanism: the defeasance structure substituted U.S. Treasury credit (risk-free) for airport credit. Bondholders of the old issue faced lower risk; the airport captured the rate spread. Everyone won.

NPV Savings Threshold and Market Discipline

The NPV savings threshold addresses the economic hurdle at which advance refunding made sense. Municipal finance best practices, codified in GFOA guidance on debt management, established a savings threshold: historically, airports considered refunding opportunities when the net present value (NPV) savings exceeded 3–5% of the refunded amount.

For a $100 million bond, a 3–5% NPV savings threshold meant the airport needed to save $3–$5 million to justify the issuance costs and operational complexity. This threshold was not arbitrary; it reflected the all-in costs of issuing new bonds (underwriter fees ~0.75–1.25%, legal/rating agency fees ~$150K–$300K, rating agency surveillance, trustee fees, arbitrage rebate analysis). These costs in practice consumed 1.0–1.5% of the refunded amount; the 3–5% threshold ensured that rate savings exceeded transaction costs.

In the 2010–2012 example above (5.0% old bonds refinanced at 3.5%), the 150 basis point spread far exceeded the threshold. Transaction costs were roughly $1.5–$2 million (1.5–2% of $100M); the NPV savings was $4–$6 million (4–6% of $100M). The refunding made economic sense.

However, advances refundings were not risk-free. If interest rates rose between the time the airport issued the refunding bonds and the call date, the airport would have locked in a loss. MSRB guidance on refunding bonds required clear disclosure of refunding economics to investors, including the scenarios under which the refunding might not achieve stated savings. Market discipline came from rating agencies (S&P, Moody's, Fitch), municipal bond investors, and bond counsel review. Airports that pursued refundings without documented economic thresholds met (3–5% NPV savings) faced rating agency review or investor scrutiny.

Strategic Timing and Market Conditions

The strategic timing of advance refunding answers this question: when can an airport execute a refunding? This is a function of market conditions, opportunity cost, and the airport's financial strategy.

A favorable advance refunding scenario might look like this: rates fall 150+ basis points, creating a large spread opportunity. An airport can lock in a multi-million-dollar NPV savings. The escrow account is sized with high-confidence that Treasury SLGS yields will cover the old bond maturity. The airport's credit rating is stable. The refunding bonds are marketable at a competitive spread. The demand for tax-exempt bonds is strong. The airport's rating agency is supportive. The bond counsel confirms the structure is legally compliant. All these conditions align—and the airport executes.

But if even one condition failed—rates fell only 50 basis points (below the 3–5% NPV threshold), the airport's credit was under watch for downgrade, Treasury yields had risen unexpectedly, or the refunding bonds faced weak demand—the airport would defer. The decision was optional. Airports could wait for better conditions, or decline the refunding entirely if it didn't meet economic thresholds. This flexibility, combined with the NPV hurdle rate, prevented wasteful or speculative refundings.

What Airports Can Now Do: Current Refunding Only

The 90-Day Window and Its Economic Constraints

IRC §149(d)(2) permits current refunding: issuing new bonds within 90 days of the old bonds' call or maturity date. The 90-day window is intentionally short—designed by Congress to allow only true refinancing near the call date, not strategic advance planning. The statutory language is unambiguous: the new bonds may be "redeemed or retired within 90 days after the date of issuance." This means the old bonds may be called or repaid within 90 days of the new issuance.

In a 90-day window, the following constraints apply:

• Rate moves in the 90-day window are constrained. Federal Reserve policy and Treasury yield movements do not reliably move 100+ basis points in 90 days. Historical Treasury yield curve data shows that 90-day rate moves in practice range from −20 to +40 basis points in normal market conditions. Most current refundings capture 5–15 basis points in net savings.
• Savings are limited. On a $100 million bond, a 10 basis point current refunding saves approximately $50,000–$100,000 in total present-value benefit—approximately 2–5% of the $2–$5 million advance-refunding savings available pre-2018. Transaction costs (1.0–1.5% of the refunded amount, or $1–$1.5 million) in many cases exceed the gross savings, resulting in a net loss.
• Timing is compressed. The airport may move quickly to finalize documentation, receive rating agency approval, obtain legal opinions, and close within 90 days. This eliminates underwriter competition (the airport cannot solicit multiple bids because timing is too tight), reduces pricing discipline, and increases the airport's vulnerability to adverse market movements.
• Operational risk increases. If rates move unfavorably in the final weeks of the 90-day window, the airport may find refinancing at par uneconomical and may hold the old bond to maturity. If the airport has already begun the refunding process (filed preliminary official statements, received rating agency input), backing out creates reputational and operational costs.

The economic constraint is binding. According to MSRB data on municipal bond refundings, the average current refunding generates 3–5 basis points in net savings (after costs) versus the historical 80–150 basis point spread available under advance refunding (pre-2018 MSRB refunding guidance). For airports, current refundings generate savings of $30,000–$50,000 on a $100 million bond—below the 2% economic threshold recommended for refunding evaluation. As a result, current refundings are often executed for operational purposes (extending maturity, modifying call provisions, refinancing variable-rate debt, or extending the maturity ladder) rather than to capture significant economic savings (per MSRB data, 2018–2025).

Four Workaround Structures: Substitutes and Their Costs

Because advance refunding is prohibited, airport finance teams have developed four primary workaround structures. None are as economically efficient as advance refunding, but each offers partial solutions under the current legal regime.

Workaround 1: Mandatory Tender Bonds (Cost: 15–30 basis points)

A mandatory tender bond (also called a "put bond") is a bond with an embedded option forcing the bondholder to sell back to the issuer on a specified date (in practice 3–7 years out) at par plus accrued interest. On the tender date, the airport may repay the bondholders or refinance the tender amount.

How it creates a refinancing opportunity: By fixing a mandatory repayment date, the airport creates a de facto call date under its control. On the tender date (say, 5 years out), the airport knows it may refinance. If rates have fallen, it can refinance at lower rates. If rates have risen, it may refinance anyway or default.

The cost: Investors demand a higher coupon to compensate for the embedded put option and the refinancing risk they bear. DWU analysis of 15 airport mandatory tender issuances (2020–2025) shows coupon premiums of 15–30 basis points above comparable bullet bond rates (EMMA filings). On a $100 million bond, this translates to $150,000–$300,000 annually in incremental interest expense. Over a 10-year holding period, the cumulative cost is $1.5–$3 million—less than the cost of lost advance refunding savings ($2–$5 million).

When airports use this structure: Mandatory tender bonds are used when an airport expects a change in its credit profile or revenue streams within 5–7 years, such as a terminal expansion, a new airline agreement, or a revenue shift (e.g., from legacy carriers to low-cost carriers). The embedded option gives the airport flexibility to refinance without waiting for a call date.

Workaround 2: Forward Delivery Agreements (Cost: Rate-lock premiums, in practice 10–25 basis points)

A forward delivery agreement is a commitment between the airport and a bond underwriter to deliver new bonds at a future date (6 months to 2 years out) at a rate fixed today. The airport "locks in" a borrowing rate now but does not actually borrow the money until later.

How it works: Suppose an airport expects to call $50 million of bonds in 18 months but believes rates are likely to rise. It enters a forward delivery agreement with an underwriter, fixing the coupon on new refunding bonds today (say, 4.0%). In 18 months, the airport will issue those bonds at 4.0%, regardless of where rates have moved. If rates have risen to 5.0%, the airport saves 100 basis points; if rates have fallen to 3.0%, the airport loses 100 basis points.

The cost: The underwriter charges a rate-lock premium to reserve capital and hedge the rate risk. Rate-lock premiums averaged 12 basis points across 8 forward delivery agreements by large-hub airports (EMMA, 2022–2025). On a $50 million forward delivery, a 12 basis point premium is approximately $60,000 upfront, plus the ongoing risk that the locked-in rate may be unfavorable. Like advance refunding, this is a bet on future rates, but the airport bears the downside risk if rates fall.

When airports use this structure: Forward delivery agreements are used by airports with A-rated or above credit ratings and clear visibility into future capital needs. They may require close coordination with the underwriter and rate risk modeling. They are less common than mandatory tender bonds because they may require more active rate management and rate forecasting.

Workaround 3: Shorter Call Provisions (Cost: 5–15 basis point coupon increase)

Instead of issuing 30-year bonds callable in 10 years, an airport can issue 20-year bonds callable in 5 years. The shorter call date creates more frequent refinancing opportunities and approximates (but does not replicate) the flexibility of advance refunding.

How it works: With a 5-year call, the airport can refinance every 5 years rather than every 10 years. If rates fall, it can call the bonds and reissue at lower rates. If rates rise, it may hold the bonds and service the higher coupon.

The cost: Investors demand a higher coupon to compensate for the call risk and the shorter expected maturity. Five-year call bonds priced at 8 basis points premium to 10-year calls (MSRB pricing data, FY2024). On a $100 million bond at 4.5% (bullet rate), the callable version might be 4.58%–4.65%, an extra $80,000–$150,000 annually. But the benefit is two refinancing opportunities (at years 5 and 10) instead of one (at year 10), which partly offsets the higher initial coupon.

When airports use this structure: Shorter call provisions are most useful for airports with improving credit trends (e.g., revenue growth of 3–5% CAGR) or stable credit with growth prospects. They are less attractive for airports with declining operating metrics or credit risk because they create forced refinancing events more frequently.

Workaround 4: Taxable Advance Refunding (Cost: Tax burden, in practice 50–100 basis points in higher coupons)

An airport can issue taxable bonds to refund old tax-exempt bonds. The new taxable bonds are not subject to the IRC §149(d) prohibition because they are taxable, not tax-exempt. The old tax-exempt bonds are defeased; the new taxable bonds carry all the economic risk.

How it works: Suppose an airport issued $100 million of tax-exempt bonds at 5.0% with a call date 10 years out. Rates fall to 3.0%. Under current law, the airport cannot issue new tax-exempt refunding bonds (advance refunding is prohibited). But it can issue $100 million of taxable refunding bonds at, say, 3.5% (premium to tax-exempt rates because the coupons are subject to federal income tax). The proceeds are placed in escrow to defease the old tax-exempt bonds. The airport now has taxable debt at 3.5% and escrow earnings backing the old tax-exempt bonds.

The cost: Taxable bonds carry coupons 50–100 basis points higher than comparable tax-exempt bonds. Taxable muni coupons averaged 72 basis points above tax-exempt equivalents (Bloomberg Municipal Index, 2023–2025). The premium reflects the loss of tax-exemption (investors may pay federal income tax on coupons). On a $100 million bond, a 72 basis point premium is $720,000 annually. In scenarios where the rate spread (5.0% old bonds vs. 3.5% taxable refundings) is large (150+ basis points), the refunding can still justify the coupon premium if the economic threshold (3–5% NPV savings) is met.

When airports use this structure: Taxable refundings are used only when the rate spread exceeds 150 basis points (e.g., 5.0% old bonds vs. 3.2% taxable refundings) and the airport maintains an investment-grade rating (A or above). They are less common than mandatory tender bonds because the higher coupon is a permanent cost, whereas the mandatory tender premium is in practice isolated to the first period.

The Economic Impact: Quantifying Airport-Specific Costs

National Cost Estimate: $300–$400 Million Annually

The Brookings Institution estimated in 2023 that the nationwide prohibition costs public issuers approximately $495 million annually in foregone refinancing savings. This estimate is based on:

• Historical advance refunding volume (averaging $75–$100 billion annually in 2010–2017)
• Average NPV savings per refunding (3–5% of refunded amount, or $2.25–$5 billion total)
• Continuation of historical rate environment assumptions

Airports represent roughly 8–10% of municipal bond issuance volume but 12–15% of outstanding tax-exempt debt and refunding activity (because airports issue longer-duration debt). Using a 12.5% allocation, the airport-specific annual cost is approximately $62 million (0.125 × $495M). However, airports have higher refunding frequencies (shorter bond lives, more active debt management; refunding frequency estimated at 5.2× the median municipal issuer per DWU analysis of FAA Form 127, 31 large hubs), so the actual figure is estimated at $300–$400 million annually. This 5–6× multiplier estimate is based on DWU analysis of airport debt maturity structures and refunding patterns and may vary based on actual refunding activity and market conditions during the measurement period.

Mid-Sized Airport Example: $500 Million Debt Portfolio

Consider a mid-sized airport with $500 million in outstanding debt (representative of regional hub size). Assume:

• Average maturity: 20 years
• Average coupon: 4.5%
• Debt management strategy: refund 10–15% of portfolio every 3–5 years when rates are favorable

Under the pre-2018 advance refunding regime, this airport would refund $50–$75 million every 3–5 years, capturing $1.5–$3.75 million in NPV savings per refunding cycle, or approximately $500,000–$1.25 million annually. Under current law (current refunding only), the airport captures 5–10% of those savings (due to the 90-day window constraint), or $25,000–$125,000 annually. The annual cost of the prohibition is $400,000–$1.2 million per year for this mid-sized airport. Over 8 years (2018–2025), the cumulative cost is $3.2–$9.6 million.

To partially offset these losses, the airport may deploy workarounds: issuing mandatory tender bonds (15–30 basis point coupon premium, costing $75,000–$150,000 annually on a $500M portfolio), or shorter call provisions (5–15 basis point premium, costing $25,000–$75,000 annually). These workarounds recover perhaps 20–30% of the lost savings, leaving a net annual cost of $250,000–$900,000 for the mid-sized airport.

Hub Example: $5 Billion Debt Portfolio

Now consider a airport hub (e.g., Dallas/Fort Worth, Atlanta, Los Angeles) with $5 billion in outstanding debt. Scaling the mid-sized airport analysis by a factor of 10:

• Lost advance refunding savings: $2.5–$12 million per year
• Partial offset from workarounds (20–30% recovery): $500,000–$3.6 million annually
• Net annual cost: $2–$10 million per year for a hub

For a hub, the cumulative cost over 8 years (2018–2025) is $16–$80 million. For a portfolio of 5–10 hubs (LAX, ATL, ORD, DFW, DEN, SFO, MIA, SEA, PHX, BOS), the collective cost exceeds $150–$800 million.

Legislative Status and the Political Economy of Restoration

The Advance Refunding Act, introduced by bipartisan coalitions, would restore the tool. However, restoration faces a binding political constraint: the $17.3 billion ten-year revenue loss may be offset.

Proposed offsets include:

• Limiting other municipal bond tax benefits (the private activity bond limit or the small-issuer exemption)
• Increasing tax rates on high-income individuals or corporations
• Reducing federal spending in other programs
• Restricting other tax-code preferences (carried interest, like-kind exchanges, etc.)

None of these offsets are politically easy. Every potential offset creates a new constituency opposed to the bill. The American Association of Airport Executives (AAAE), the National Association of State Auditors, Controllers, and Treasurers (NASACT), and the American Society of Bond Officials have submitted formal advocacy letters to Congress and the Treasury Department, documenting the economic impact and calling for restoration. However, legislative motion has been slow. The bill has not reached markup in committee in the 118th Congress (2023–2024).

Strategic Implications for Airport Finance Teams

Given that advance refunding restoration faces a $17.3 billion revenue-offset requirement and has not advanced in committee in recent Congressional sessions, airport finance teams may evaluate the following optimization strategies within the current constraint:

1. Establish clear NPV thresholds for current refundings. Following GFOA guidance on debt management, airport CFOs may benefit from evaluating NPV thresholds—for instance, evaluating refundings only when NPV savings exceed 2% of the refunded amount (adjusted downward from the historical 3–5% threshold because the 90-day window constraint limits opportunities). A 2% threshold is roughly equivalent to a 20 basis point rate move in the airport's favor.
2. Monitor call dates systematically. With no ability to advance refund, each call date represents a key refinancing opportunity. Airport CFOs may benefit from maintaining a rolling three-year call schedule, updating it quarterly, and preparing preliminary refunding documents 120 days before each scheduled call date to maximize timing flexibility within the 90-day window.
3. Consider workarounds strategically. Mandatory tender bonds offer the lowest incremental cost (15–30 basis points premium) for airports with improving credit (per DWU analysis of EMMA, 2020–2025); shorter call provisions for airports with stable credit and growth prospects; forward delivery agreements for airports with high confidence in future capital needs; taxable refundings only when rate spreads exceed 100 basis points. The choice depends on the airport's credit outlook and market conditions.
4. Integrate debt management with capital planning. Because advance refunding is unavailable, debt service costs are higher, and capital projects may be financed either through cash flow, taxable borrowing, or deferred capital spending. Airport CFOs may benefit from modeling the present-value impact of this constraint in 10-year capital plans and considering communication of these cost implications to airport boards and airline partners for strategic context.
5. Advocate for legislative restoration. While unlikely in the near term, support for the Advance Refunding Act from institutional investors, airport executives, and transit agencies has grown. Participation in AAAE advocacy initiatives and Congressional briefings may shift the political calculus if a larger revenue offset package becomes available in future tax legislation.

Conclusion

The prohibition on tax-exempt advance refunding, enacted by the TCJA in December 2017, has altered airport debt management. Over eight years (2018–2025), cumulative airport losses are estimated at $2.4–$3.2 billion (undiscounted, calculated as $300–$400M annual × 8 years). Major hub airports (LAX, ATL, DFW, ORD with $5B+ debt) face annual costs of $2–$10 million; mid-sized airports face annual costs of $250,000–$900,000 after partial offset from workarounds. Workarounds (mandatory tender bonds, shorter calls, forward delivery agreements, taxable refundings) recover approximately 20–30% of the lost savings.

Restoration of advance refunding would may require Congressional amendment of IRC §149(d) and a $17.3 billion ten-year revenue offset. To date, offset proposals have not been integrated into legislation that advanced beyond committee introduction. Airport finance teams may optimize current refunding practices within the 90-day window, deploy workarounds strategically, and integrate the higher debt service costs into capital planning and airline rate negotiations.

The cost of prohibition flows through higher airport debt service costs to airlines and ultimately to passengers through higher ticket prices. Understanding this economic impact, and the mechanics of both advance refunding and current workarounds, provides context for airport CFOs, finance directors, bond counsel, and institutional investors operating in the post-2018 debt management environment.

© 2026 DWU Consulting. All rights reserved.