How Regulation Z Calculates the Finance Charge on a Loan

When you see a finance charge and an APR printed on a loan disclosure, those two numbers are not arbitrary — they follow a specific federal formula. Section 1026.4, the rule that defines what counts as a finance charge, lives inside 12 CFR Part 1026, better known as Regulation Z, the CFPB's rule implementing the Truth in Lending Act. This walkthrough uses a single hypothetical fixed installment loan to show, step by step, how a creditor turns a note amount and a fee into the finance charge and APR you'd actually see on paper.

The building blocks Regulation Z starts with

Regulation Z's finance-charge rule governs creditors extending closed-end or open-end consumer credit covered by the Truth in Lending Act, and it sets out what must be counted as part of the cost of credit. To see the formula in action, RB built a simple hypothetical: a consumer borrows against a $10,200 note that carries a stated, or 'note,' interest rate of 10% per year, compounded monthly, and that note amount includes a $200 origination fee that Regulation Z treats as a finance charge because it's financed into the loan. The loan is repaid in 48 equal monthly installments. These are RB's own illustrative numbers, not a regulator's published example, chosen only to make the mechanics easy to follow.

Worked example: from note amount to amount financed

Start with the $10,200 note amount, which already includes the $200 financed origination fee. Subtract that $200 prepaid finance charge, and the amount financed comes out to $10,000. In this illustrative transaction, that's the §1026.18(b) calculation applied here — starting from the note amount with no separate cash-price or down-payment step, since none applies to this loan.

• face amount: 10200
• prepaid finance charge: 200
• Formula: face amount - prepaid finance charge
• Result: 10000

Step two: amortizing the note to find the monthly payment

Next, the creditor amortizes the full $10,200 note — not the smaller amount financed — at the stated 10% annual rate, divided into a monthly rate of 10% divided by 12, over the 48-month term. Running that standard level-payment amortization formula produces a monthly installment of about $258.70.

• face amount: 10200
• i: 0.008333333333333333
• n: 48
• Formula: face amount*i/(1-(1+i)^(-n))
• Result: 258.69835103442205

Step three: totaling all 48 payments

Multiply that $258.70 monthly payment by the 48 scheduled payments, and the borrower ends up paying about $12,417.52 in combined principal and interest over the life of the loan, assuming no prepayment or late fees.

• payment: 258.69835103442205
• n: 48
• Formula: payment*n
• Result: 12417.520849652257

Step four: deriving the disclosed finance charge

Regulation Z's disclosure items connect the amount financed and the total of payments directly to the finance charge: subtract the $10,000 amount financed from the $12,417.52 total of payments. The result is a disclosed finance charge of $2,417.52. That figure bundles together everything the loan actually costs the borrower beyond the money they received — both the ordinary interest that accrues over 48 months and the $200 origination fee that was financed into the note.

• total of payments: 12417.520849652257
• amount financed: 10000
• placeholder: 0
• Formula: total of payments - amount financed
• Result: 2417.5208496522573

Step five: why the APR is higher than the note rate

The APR isn't simply the note's stated 10% rate restated as a percentage — it's a separate calculation that solves for the discount rate that makes the 48 payments of $258.70 equal in present value to the $10,000 amount financed, rather than the $10,200 face amount. Solving that equation iteratively gives a monthly rate of about 0.9208 percent. Appendix J's general rule says you annualize that by multiplying by 12, which produces a disclosed APR of about 11.05 percent. That APR sits meaningfully above the loan's 10% note rate precisely because the $200 financed fee shrinks the amount financed without shrinking the payments, and the result lands comfortably within the regulation's 1/8-point accuracy tolerance for a regular transaction once rounded.

• j: 0.00920837494865417
• Formula: j*12*100
• Result: 11.050049938385003

Document anatomy: how the five disclosure figures fit together

• Note (face) amount: $10,200, including the $200 financed origination fee
• Amount financed: $10,000, found by subtracting the $200 prepaid finance charge from the $10,200 note amount under §1026.18(b)
• Monthly payment: about $258.70, from amortizing the $10,200 note at 10% annually over 48 months
• Total of payments: about $12,417.52, the sum of all 48 scheduled payments, assuming no prepayment or late fees
• Finance charge: about $2,417.52, the total of payments minus the amount financed
• Annual percentage rate: about 11.05 percent, the annualized discount rate under Appendix J that equates the payment stream to the amount financed

How the five disclosure figures relate to one another in this example.

Measure	Value	What drives it
Stated note rate	10% per year, compounded monthly	Set by the lender on the $10,200 note before fees are factored in
Disclosed APR	about 11.05%	Annualized discount rate that equates the $258.70 payments to the $10,000 amount financed, per Appendix J
Gap between the two	about 1.05 percentage points	Driven by the $200 financed origination fee shrinking the amount financed without changing the payment amount

Note rate versus the disclosed APR in this hypothetical loan.

Key takeaways

• The finance-charge rule discussed here, §1026.4, sits inside Regulation Z, the Truth in Lending Act's implementing regulation for covered consumer credit
• Amount financed is found by subtracting prepaid finance charges, like a financed origination fee, from the note's face amount — in this example, $10,200 minus $200 equals $10,000
• The monthly payment is calculated by amortizing the full note amount at the stated note rate, producing about $258.70 a month in this 48-month example
• The disclosed finance charge equals the total of all payments minus the amount financed — about $2,417.52 here, covering both interest and the financed fee
• The APR discounts the payment stream back to the amount financed rather than the note's face amount, which is why this loan's roughly 11.05% APR runs higher than its 10% stated note rate

Frequently asked questions

Why is the APR higher than the loan's stated interest rate in this example?

The APR is higher because it's calculated against the $10,000 amount financed, not the $10,200 face amount of the note, while the monthly payments were set based on the full $10,200.

Discounting those same payments back to a smaller amount financed produces a higher implied rate — about 11.05% annualized versus the 10% stated note rate — and that gap is driven entirely by the $200 financed origination fee in this hypothetical.

Does the finance charge include the origination fee, or just interest?

The face amount of the note and the amount financed differ in this example because the $200 financed origination fee is rolled into the note and then subtracted out under §1026.18(b).

Could I use these same steps to check a real loan disclosure?

Sources

• www.consumerfinance.gov