How the SBA 504 Loan Calculation Actually Works
An SBA 504 loan is not a single loan with a single rate. It is a coordinated financing package involving three parties, and the monthly payment you will actually write is the sum of two separate amortizations at two different rates over potentially two different terms. Getting this right matters, because the difference between a naive single-rate calculation and the correct split calculation is often several hundred dollars a month.
Step 1 — Calculate the bank portion
A conventional bank or credit union funds 50% of total project cost. This portion is not SBA-guaranteed, sits in first lien position, and is priced at whatever the lender offers — typically 7% to 8% for owner-occupied commercial real estate in mid-2026. Terms run 10 to 25 years, and some banks structure this portion with a balloon at year 10 even when amortizing over 25 years.
Step 2 — Calculate the CDC portion
A Certified Development Company funds 40% of project cost through an SBA-guaranteed debenture. This is the piece most borrowers think of as "the SBA loan." The rate is fixed for the entire term and is set on a monthly pricing date published by the SBA. Unlike a 7(a) loan, it never reprices — which is the core structural advantage of the 504 program.
Step 3 — Add the two payments
Your total monthly obligation is the bank payment plus the CDC payment. The remaining 10% of the project is your equity contribution and generates no payment. Some borrowers also compute a blended effective rate for comparison against a single 7(a) quote — that is the weighted average of the two rates by their respective principal balances.
Current SBA 504 Rates — July 2026
| CDC Term | Effective Rate | Rate Type | Includes |
|---|---|---|---|
| 25 years | 6.17% | Fixed for life of loan | SBA guarantee + CDC servicing + CSA fee |
| 20 years | 6.20% | Fixed for life of loan | SBA guarantee + CDC servicing + CSA fee |
| 10 years | 6.19% | Fixed for life of loan | SBA guarantee + CDC servicing + CSA fee |
| Bank portion (reference) | 7.0% – 8.0% | Lender-set, fixed or variable | Lender fees separate |
CDC rates are tied to the 10-year Treasury note and reset on a monthly SBA pricing calendar. The rate you receive is locked on the debenture funding date, not the date you apply.
Worked Examples at Three Project Sizes
$750,000 project — 25-year terms, 10% down
| Component | Amount | Rate | Monthly |
|---|---|---|---|
| Bank portion (50%) | $375,000 | 7.25% | $2,710 |
| CDC portion (40%) | $300,000 | 6.17% | $1,963 |
| Down payment (10%) | $75,000 | — | $0 |
| Total | $675,000 financed | ~6.77% blended | $4,673/mo |
$1,500,000 project — 25-year terms, 10% down
| Component | Amount | Rate | Monthly |
|---|---|---|---|
| Bank portion (50%) | $750,000 | 7.25% | $5,420 |
| CDC portion (40%) | $600,000 | 6.17% | $3,927 |
| Down payment (10%) | $150,000 | — | $0 |
| Total | $1,350,000 financed | ~6.77% blended | $9,347/mo |
$1,500,000 special-purpose project — 15% down
| Component | Amount | Rate | Monthly |
|---|---|---|---|
| Bank portion (50%) | $750,000 | 7.25% | $5,420 |
| CDC portion (35%) | $525,000 | 6.17% | $3,436 |
| Down payment (15%) | $225,000 | — | $0 |
| Total | $1,275,000 financed | ~6.81% blended | $8,856/mo |
Note how the higher down payment reduces the CDC portion, not the bank portion. The bank stays at 50% of project cost; the borrower's extra equity displaces CDC debenture dollars.
SBA 504 vs 7(a) — The Cost Difference on Real Estate
For a $1,350,000 financing need on owner-occupied commercial real estate over 25 years:
| Program | Structure | Rate | Monthly | Total Interest |
|---|---|---|---|---|
| SBA 504 | Bank 50% + CDC 40% | ~6.77% blended | $9,347 | $1,454,100 |
| SBA 7(a) | Single loan | 10.50% variable | $12,741 | $2,472,300 |
| 504 advantage | — | −3.73 pts | −$3,394/mo | −$1,018,200 |
The 504 program saves roughly $3,394 per month and over $1 million in total interest on this deal. That gap is the entire reason the extra closing complexity of coordinating a bank and a CDC is worth it on larger real estate transactions. Below roughly $1 million in project size, the savings narrow and the operational overhead often stops making sense.
What SBA 504 Loans Can and Cannot Fund
Eligible Uses
Purchasing owner-occupied commercial real estate (business must occupy at least 51% of existing buildings, 60% of new construction). Ground-up construction. Building improvements and renovations. Long-life machinery and equipment. Refinancing existing debt that originally financed eligible fixed assets.
Ineligible Uses
Working capital. Inventory purchases. Payroll. Marketing expenses. Business acquisition, including goodwill. General debt consolidation. Rental or investment real estate where the borrower does not occupy the majority of the space. If any of these are part of your project, 7(a) is the program you need.
Special-Purpose Property
Hotels, motels, gas stations, restaurants, car washes, bowling alleys, self-storage, and similar single-use properties require a 15% down payment instead of 10%. If the business is also a startup under two years old, the requirement rises to 20%.
Frequently Asked Questions — SBA 504 Calculator
Compare Against a 7(a) Quote
Run the same project through the 7(a) calculator to see the total cost difference on your specific numbers.
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