Incremental Borrowing Rate Under ASC 842: Set It Right

Ask ten accountants how they set the incremental borrowing rate on a lease and you'll get ten different spreadsheets. It's the one input in ASC 842 that nobody hands you on a plate — you have to build it yourself, defend it to your auditor, and live with it for the rest of the lease.

That matters more than it sounds. The incremental borrowing rate, or IBR, is the discount rate you use to turn a stream of future lease payments into a single number today. Push the rate up and the lease liability shrinks. Push it down and the liability — plus the right-of-use asset sitting next to it — grows. Get it wrong by even a couple of percentage points and your balance sheet tells a noticeably different story.

• The IBR is what you discount lease payments with whenever the rate implicit in the lease isn't known — which is almost always, in practice.
• A higher IBR produces a smaller lease liability and a smaller ROU asset; a lower IBR produces bigger numbers on both.
• Build it from your own secured borrowing rate (or credit rating), a risk-free yield curve matched to the lease term, and an adjustment for collateral and credit risk.
• Private companies and not-for-profits can elect a risk-free rate instead, asset class by asset class, since ASU 2021-09.
• Public companies don't get that shortcut — they have to estimate a genuine incremental borrowing rate for every lease.

What is the incremental borrowing rate, and why does it carry so much weight?

Under ASC 842, the IBR is the rate a lessee would have to pay to borrow, on a secured basis, over a term similar to the lease, an amount similar to the lease payments, in a similar economic environment. IFRS 16 defines it in almost the same terms for its own lessees. It's a hypothetical borrowing rate — you're not actually taking out a loan, you're estimating what one would cost you if you were.

The reason it carries so much weight is structural. The lease liability is the present value of the remaining payments, discounted at this rate. The right-of-use asset is then built from that liability, plus any prepaid rent and initial direct costs, minus incentives received. So one input — the discount rate — effectively sets the opening size of two separate balance sheet lines at once, not just one.

That's also why the number attracts scrutiny. A higher rate flattens the liability, which can flatter leverage ratios and debt covenants. Auditors know this, and they'll expect a documented, defensible build-up rather than a rate that was quietly nudged upward to hit a target.

When are you actually forced to use the IBR?

ASC 842 technically prefers a different number first: the rate implicit in the lease. That's the rate that equates the present value of the lease payments plus any guaranteed residual value to the fair value of the underlying asset plus the lessor's initial direct costs.

In theory, that's a cleaner number. In practice, lessees almost never have it. It requires knowing the lessor's assumed residual value and their initial direct costs, and lessors rarely disclose either one — they have no obligation to and usually no commercial reason to. So for the overwhelming majority of real-world leases, especially real estate, the rate implicit in the lease simply isn't readily determinable, and the IBR takes over by default.

The exception tends to be certain equipment and vehicle finance arrangements, where a captive lessor or dealer sometimes states an implicit rate directly in the contract. If that number is genuinely disclosed and derivable, use it. Otherwise, assume you're building an IBR.

How do finance teams actually build a defensible IBR?

Most companies don't pull one number off a data terminal and call it done. They assemble the rate from a handful of components, then document the logic so it survives an audit.

• Start with your own credit profile: your most recent secured borrowing, such as a term loan or asset-based facility, if you have one — or a proxy built from your credit rating if you don't.
• Layer in a risk-free or treasury yield matched to the lease term. The 5-year US Treasury yield sat at roughly 4.28% in mid-July 2026 — you'd pick whatever maturity point on the curve matches your lease term.
• Adjust for collateralization. The IBR assumes a secured borrowing, and the leased asset itself effectively functions as informal collateral, so secured rates typically run below unsecured ones.
• Add your incremental credit spread — the extra yield the market would demand for your specific credit risk, term, and currency, layered on top of the risk-free base.

What happens if you get the rate wrong? A worked example

Picture a mid-size company signing a five-year office lease: $10,000 a month, paid at the start of each month, 60 payments in total, no lease incentives or initial direct costs to keep the arithmetic clean.

Discount those payments at a 5% annual IBR and the lease liability at commencement comes to about $532,100. Discount the exact same 60 payments at a 9% annual IBR instead, and the liability drops to about $485,300 — roughly $46,800, or 8.8%, smaller. With no incentives or costs in the mix, the initial ROU asset moves by the same amount, on the same side of the balance sheet as the liability.

Nothing about the cash paid to the landlord has changed. What's changed is how big the liability, the asset, and the resulting interest and amortisation expense look on paper for the next five years. If you want to see this play out on your own numbers rather than a hypothetical one, our guide to calculating the ROU asset and lease liability walks through the full mechanics step by step.

The risk-free rate practical expedient: who gets to use it, and how

ASC 842-20-30-3 gives certain lessees a shortcut: an accounting policy election to use a risk-free rate, such as a matched-maturity treasury yield, instead of building an IBR from scratch. It's only available to lessees that are not public business entities — private companies and not-for-profit organisations.

Before November 2021, that election was all-or-nothing across the entire entity, which put off plenty of companies that only wanted it for some of their leases. ASU 2021-09 fixed that: the election can now be made by class of underlying asset instead. A private company could elect the risk-free rate for its office real estate while still building a proper IBR for equipment or a vehicle fleet, where the size of the gap matters more. Whichever classes are elected have to be disclosed.

The trade-off is worth knowing before you take the shortcut: a risk-free rate is generally the lowest rate on the table, so it tends to produce the largest possible liability and ROU asset. IFRS 16 has no equivalent expedient at all — every IFRS 16 lessee has to estimate a genuine incremental borrowing rate, which is one of several places where IFRS 16 and ASC 842 quietly diverge.

Model both rates before you commit

Whatever rate you land on, it's worth seeing the effect before it's locked into your books. Plug your actual payment schedule into the free calculator and you'll get the lease liability, the ROU asset, and a full amortisation schedule instantly — try it at 5%, then again at 9%, and watch exactly how much the numbers move.

It's free for a single lease. If you're running this across a whole portfolio, or want your finance systems and AI agents pulling the same schedules and journal entries automatically, that's what the metered API is for.

Frequently asked questions

Sources

• FASB ASU 2021-09: Discount Rate for Lessees That Are Not Public Business Entities
• Journal of Accountancy: FASB risk-free rate rule cuts costs for nonpublic lessees
• RSM US: Calculating the incremental borrowing rate as a lessee
• IFRS Interpretations Committee: Lessee's Incremental Borrowing Rate (IFRS 16), September 2019
• FRED: Market Yield on U.S. Treasury Securities at 5-Year Constant Maturity (DGS5)