CMBS Loan for Office Building: A Broker's Guide

A CMBS loan for an office building is non-recourse, fixed-rate permanent debt secured by the office's cash flow, pooled with other commercial mortgages, and sold to investors as commercial mortgage-backed securities (CMBS). Office CMBS loans typically range from $5 million to $100+ million, with 5, 7, or 10-year fixed terms, 25 to 30 year amortization, 55% to 65% LTV, 1.30x to 1.45x DSCR, and a 10% to 12% debt yield floor. Pricing is a spread over Treasury benchmarks, and prepayment is locked through defeasance or yield maintenance.

The CMBS market for office has been the most contested segment of commercial real estate finance for the past three years. Hybrid work, elevated sublease availability, slower return-to-office trends in coastal urban markets, and rising debt yields have all squeezed the office CMBS box. CMBS lenders are still active in office, but only for specific subtypes: medical office, single-tenant credit, government-leased, suburban office in growth markets, and trophy Class A with long WALT and credit tenants. This guide walks through how to identify a fundable office CMBS deal, package it, and place it with the right lender from a broker's seat.

Which Office Buildings Qualify for CMBS Today

CMBS lenders differentiate sharply between office subtypes. The same dollar amount of loan request gets very different treatment depending on which subtype the deal sits in.

Medical office building (MOB) is the strongest office subtype for CMBS today. Healthcare tenants have long leases (often 10 to 15 years), high renewal rates, sticky tenancy due to capital investment in build-out, and counter-cyclical demand. MOBs anchored by hospital systems, surgical centers, or large multi-specialty groups get the most competitive CMBS pricing. Leverage on stabilized MOB can reach 65% to 70% LTV at 10% to 10.5% debt yield, the high end of office CMBS sizing today.

Single-tenant credit office is the next strongest subtype. Properties leased to investment-grade tenants (Standard and Poor's BBB or higher, or Moody's Baa2 or higher) on long-term net leases with 10+ years remaining get treated more like credit-tenant lease (CTL) than traditional office. Leverage can reach 65% to 70% LTV if the tenant credit and lease term support it. Common credit tenants include Fortune 500 corporate HQs, federal government agencies, large law firms with long leases, and accounting firms.

Government-leased office (GSA) falls into a similar category. The U.S. federal government (General Services Administration) leases office space on long-term contracts; CMBS lenders treat GSA leases as essentially credit tenant. The key risk is contract renewal rather than tenant credit. GSA-leased office is one of the few subtypes where CMBS execution remains broadly available.

Suburban office in growth markets has held up better than urban office in most submarkets. CMBS lenders quote suburban office in Sun Belt growth markets (Nashville, Charlotte, Raleigh-Durham, Tampa, Austin, Phoenix, Salt Lake City) where return-to-office trends are stronger, vacancy is lower, and sublease availability is more limited. Suburban office in legacy coastal markets is more selective.

Trophy Class A urban office with stabilized rent rolls, low near-term rollover, and a WALT of 7+ years still attracts CMBS, but at lower leverage and tighter terms than 2019. Lenders want to see strong tenant credit across the rent roll, current rents at or below market, and limited concentration risk.

Multi-tenant Class B office, large-floorplate office in weak return-to-office markets, and office with concentration risk are the most challenging subtypes for CMBS today. Many of these deals do not get a CMBS quote and need to look at bank balance sheet, debt fund, or bridge alternatives.

Typical CMBS Terms for an Office Building

Use the DSCR calculator, debt yield calculator, NOI calculator, and commercial mortgage calculator to size the loan against all three constraints (LTV, DSCR, debt yield) and take the lowest before going to market.

How CMBS Office Loans Are Sized

Three constraints determine the maximum CMBS loan amount on an office building, and the lender sizes off the lowest:

• Loan-to-value (LTV): 55% to 65% of the as-stabilized appraised value. Lenders apply a market cap rate plus a stress adjustment when valuing the property; aggressive cap rate assumptions on the appraisal get cut back.

• Debt service coverage ratio (DSCR): 1.30x to 1.45x on underwritten NOI at the proposed loan rate. Lenders use a stressed underwriting rate, not the actual coupon, which tightens DSCR sizing.

• Debt yield: 10% to 12% on underwritten NOI. Debt yield is the most binding constraint on office deals today and is the metric lenders refer to when discussing sizing.

For a Class A medical office building with strong hospital system tenancy, leverage may run to the LTV cap of 65% to 70%. For a multi-tenant Class B urban office in a weak return-to-office market, debt yield will likely cap the loan at 50% to 55% LTV even if the LTV box would allow more. The broker should size the deal three ways and present the result to the sponsor so the financing structure (CMBS first, bridge first, mezz fill, or alternative execution) gets decided upfront.

Due Diligence Unique to Office

Standard CMBS due diligence covers sponsor financials, property condition, and Phase I environmental. Office adds seven sector-specific items that CMBS lenders focus on:

Tenant Credit and Lease Term Analysis

Every tenant occupying more than 5,000 square feet or paying more than 5% of total rent gets a credit review. CMBS lenders want to see public credit ratings where available (S&P, Moody's, Fitch), financial statements for non-rated tenants, parent guarantees on subsidiary leases, and trailing payment history. The weighted average lease term (WALT) across the rent roll is the single most important office metric for CMBS underwriting; deals with a WALT below 5 years face significant sizing or pricing penalties.

Rollover Schedule and Concentration Risk

Lenders chart the rent roll by year of expiration and stress test what happens if major tenants do not renew. Concentration risk from a single tenant rolling within 12 to 18 months of CMBS loan maturity is a frequent deal-killer. Pre-CMBS renewal negotiation with major tenants is often the right move to extend WALT before closing.

Current Rents vs Market Rents

CMBS lenders mark the rent roll to current market rents. If the in-place rents are 20% above current submarket comps, the lender will underwrite to a lower rent at next rollover, which reduces NOI and loan sizing. Brokers should compare the rent roll to current submarket comps before quoting a deal size to the sponsor.

Sublease Availability

Available sublease space in the building, in competing buildings in the submarket, and in the broader submarket is a key office indicator. High sublease availability signals tenant downsizing pressure and weak releasing economics. Lenders factor sublease availability into their stress tests on TI/LC reserves and re-leasing assumptions.

TI/LC and CapEx Reserves

Office TI/LC is materially higher than retail or industrial. Office TI for a new tenant typically runs $40 to $100 per square foot for general office, higher for medical and life science. Leasing commissions run 4% to 6% of total lease value. CapEx reserves on office cover elevator modernizations, HVAC upgrades, lobby and common area renovations, and amenity package upgrades that increasingly drive tenant attraction. CMBS lenders typically reserve 15 to 25 cents per square foot per year for office CapEx and TI/LC.

Return-to-Office and Submarket Trends

While not a hard underwriting item, return-to-office metrics inform how lenders view a submarket. Submarkets with strong return-to-office trends (most Sun Belt markets, suburban markets, medical and life science clusters) get tighter pricing than submarkets where return-to-office has lagged.

Building Class and Capital Improvements

Building Class (A, B, C) and recent capital improvements signal long-term tenant appeal. Office without recent lobby, amenity, and mechanical upgrades faces pressure from newer competition. CMBS lenders may require additional CapEx reserves on Class B office to fund expected improvements over the loan term.

Deal Structure: Origination Through Securitization

A CMBS office loan moves through five phases from application to securitized servicing:

1. Application and term sheet: The broker shops the deal to multiple CMBS lenders. Lenders provide preliminary term sheets based on rent roll, financials, and property condition. Sponsor selects the best term sheet and signs an application with a deposit.

2. Third-party reports: Phase I environmental, property condition assessment, appraisal, and seismic (in seismic zones) are ordered. Each report takes 2 to 4 weeks. Findings can adjust loan sizing.

3. Underwriting and closing: The lender's underwriting team reviews tenant credit, lease abstracts, rollover schedule, and market data. Final loan documents are negotiated and the loan closes. Closing typically runs 60 to 90 days from application.

4. Warehouse and pooling: The lender holds the loan on a warehouse line for 30 to 90 days while assembling a pool of similar loans for securitization. During this period, the loan is technically on the lender's balance sheet.

5. Securitization and servicing: The pool of loans is sold to investors as CMBS bonds. A master servicer handles day-to-day administration, and a special servicer takes over if the loan defaults or transfers to special servicing. The sponsor's day-to-day touchpoint becomes the master servicer for the life of the loan.

For more on the securitization process, see the CMBS glossary entry and the brokers guide to CMBS lending.

Pricing: How Office CMBS Spreads Have Moved

CMBS office spreads to Treasuries have widened materially since 2019 and remain elevated. For top-quality office (medical office, single-tenant credit, GSA), spreads typically run 200 to 275 basis points over the matched Treasury benchmark. For multi-tenant Class A office in healthy markets, spreads run 250 to 325 basis points. For Class B office and weaker submarkets, spreads can run 325 to 400+ basis points, and many deals do not get quoted at all.

Coupon rates are spread plus benchmark. With the 10-year Treasury in the 4% to 4.5% range, all-in fixed rates on office CMBS today commonly run 6.5% to 8.5%, depending on subtype. Run the commercial mortgage calculator and the DSCR calculator at the projected coupon to confirm the deal pencils before going to market.

Prepayment: Defeasance vs Yield Maintenance

CMBS office loans almost always carry one of two prepayment mechanisms: defeasance or yield maintenance. Both lock the loan in for the full term in practical terms.

Defeasance requires the borrower to purchase a portfolio of U.S. Treasuries that replicates the remaining payments on the loan. The Treasuries replace the property as collateral, and the property is released. Defeasance costs include the cost of the Treasury portfolio, servicer fees, accountant and attorney fees, and rating agency confirmation costs. In a rising-rate environment, defeasance costs come down. In a falling-rate environment, defeasance costs go up. The defeasance cost estimator at janover.pro/calculators provides a rough sizing.

Yield maintenance requires a single payment equal to the present value of the remaining interest payments, discounted at a stated Treasury rate. Yield maintenance is simpler and faster than defeasance but typically costs slightly more upfront. The yield maintenance calculator at janover.pro/calculators provides a rough estimate.

Most office CMBS loans use defeasance for the locked period and have an open prepayment window (typically 3 to 6 months) before maturity. Plan refinance or sale timing around the prepayment mechanism.

Common Pitfalls on Office CMBS Deals

• Tenant concentration with rollover near CMBS maturity: A large tenant whose lease ends within 12 to 18 months of CMBS loan maturity is the most common deal-killer. Renew or backfill that tenant before going to CMBS, or expect downsizing or decline.

• Overstated underwritten rents: CMBS lenders mark to current submarket comps. If in-place rents are above market, the lender will haircut the rent roll at next rollover, reducing NOI and loan sizing.

• Understated TI/LC and CapEx reserves: Office TI runs $40 to $100+ per square foot for new leases. Underwriting TI/LC reserves at $10 per square foot per year on a building with 30% near-term rollover gets a lender pushback.

• Missing or weak market study: CMBS lenders want submarket vacancy, absorption, rent trends, and sublease availability data. A package without a market study or with a stale one gets sized conservatively.

• Aggressive cap rate on as-stabilized value: Appraisals based on cap rate compression assumptions get cut. Lenders apply a stress adjustment to cap rates that haircuts the appraisal.

• Ignoring submarket return-to-office trends: Office in weak return-to-office markets gets priced wide and sized small. Acknowledging this upfront in the deal package and showing the building's specific resilience (strong tenant credit, recent leases, low sublease availability) helps.

• Not benchmarking debt yield first: Debt yield is the binding constraint on office CMBS today. Sizing the deal to LTV first and assuming debt yield will work is a common rookie error.

CMBS Office vs Bank Office vs Life Company Office

For most stabilized office deals above $5 million with limited near-term rollover, CMBS is the cheapest fixed-rate execution. For smaller deals, deals with significant rollover, or deals needing flexible prepayment, bank balance sheet is often the better execution. For trophy single-tenant credit office, life companies usually price tighter than CMBS. See the life company loans guide and the broker guide to office finance.

How Janover Pro Connects Borrowers to Office CMBS Lenders

CMBS office is a relationship business. Not every CMBS lender quotes office today, and within those who do, lenders specialize by office subtype, loan size, market, and sponsor profile. Matching the deal to the right lender is the broker's job, and the most efficient way to do it is with a structured lender database that filters by execution type, property type, loan size, and submarket.

Janover Pro's lender platform includes thousands of verified lenders, with CMBS lenders tagged by office appetite, deal size, and geographic footprint. Brokers create a structured deal profile, pull a matched lender list, and distribute the deal package to multiple lenders simultaneously. Responses, term sheet requests, and follow-up conversations live in a unified inbox. See data-driven lender sourcing.

For a $15 million medical office building, the right CMBS shops are the conduit lenders with active healthcare programs. For a $50 million trophy Class A urban office, the right lenders are larger conduit shops or single-asset single-borrower (SASB) lenders. For a $7 million suburban office with limited rollover, the right execution may be a smaller conduit lender or a bank balance sheet. Janover Pro's filter logic surfaces the appropriate lenders by deal type and saves the broker the cold-outreach cycle.

Broker Tips for Placing These Deals

Office CMBS deals sell on tenant credit, lease term, and rollover risk. Package the deal with those three items front and center.

Lead with the rent roll and tenant credit summary. The first 5 pages of the deal package should show the rent roll, tenant credit ratings or financial summaries, WALT, rollover schedule by year, and a market rent comparison. CMBS lenders make initial sizing decisions off this data; lead with it rather than burying it in the financial appendix.

Pre-empt rollover concerns. If a major tenant is rolling within the loan term, get the renewal LOI or executed extension done before going to CMBS. If a renewal is in negotiation, show the progress in the package. If a tenant is going to vacate, present a backfill plan with leasing momentum and target tenants.

Benchmark debt yield first. Run the deal at projected stabilized NOI and the target loan amount. If debt yield is below 10% to 12% (depending on subtype), the loan size will be cut. Adjust the request before going to market or position the deal for a smaller permanent loan plus mezz or preferred equity.

Document submarket fundamentals. Pull current submarket vacancy, absorption, rent trends, and sublease availability from CoStar, JLL, CBRE, Cushman, or Newmark. Strong submarket data supports the rent roll and helps the lender underwrite to the in-place rents.

Target the right lenders. Match the deal to lenders quoting comparable office in the submarket. Not every CMBS lender quotes office today, and the lenders who do have specific appetite by subtype. Targeting the wrong lender wastes everyone's time and gets the deal stale.

Key Metrics to Verify Before Going to Market

• Weighted average lease term (WALT) across the rent roll

• Rollover schedule by year, with tenant credit rating and current rent per square foot

• In-place rent per square foot vs current submarket market rent

• Trailing 12-month NOI and pro forma stabilized NOI

• Debt yield at projected loan amount on underwritten NOI

• DSCR at projected loan amount, projected coupon, and stress underwriting rate

• Loan-to-value (LTV) on as-stabilized appraised value with stressed cap rate

• TI/LC reserve per square foot per year vs expected rollover

• CapEx reserve per square foot per year vs property condition findings

• Submarket vacancy, absorption, and sublease availability data

• Tenant credit ratings (S&P, Moody's, Fitch) or financial statements for major tenants

• Phase I environmental findings and any Phase II contingency

Frequently Asked Questions