Financing exam concepts
Fixed-rate vs. adjustable-rate mortgage
A fixed-rate borrower can see a higher bill without a rate change. An ARM borrower can see a higher rate even after its index falls. Both make sense once you separate the note rate, the adjustment limits and the rest of the payment. Start there before calculating a reset.
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The short answer
A fixed-rate mortgage keeps its contract interest rate unchanged. An adjustable-rate mortgage, or ARM, permits changes on a stated schedule. Index plus margin gives the fully indexed rate, but caps, floors and rounding can alter the permitted reset. A fixed rate does not fix taxes or insurance, and an ARM rate cap does not necessarily cap the total monthly payment.
Reviewed October 26, 2026. PSI lists ARM loans in National IV.B.3. The whole Financing domain has 10 scored national broker questions; that is not a quota for this comparison. All rates and balances below are fictional teaching inputs, not current offers, index quotations or personal loan recommendations.
Read the terms, calculate the permitted rate, then check the payment
- Separate the note rate from the bill. A typical fully amortizing fixed-rate loan has level scheduled principal and interest. Escrowed taxes, insurance and other charges can change. A special payment feature can also matter without turning every fixed-rate loan into an ARM.
- Record the timeline. Identify the initial fixed period, first rate-change date, later frequency, payment dates and full maturity. In common notation, 5/1 means five initial years followed by annual adjustments; 5/6m means five initial years followed by six-month adjustments. Neither makes the loan a five-year maturity.
- Use the contract’s index observation and margin. Add percentage points to find the fully indexed rate. The starting rate may differ from that result, so a discounted initial rate can expire even if the benchmark is unchanged. Do not substitute today’s index for a specified lookback value.
- Apply rounding and limits in the order the note requires. Distinguish the first-adjustment cap, later periodic cap, lifetime ceiling and any floor or downward-change limit. A two-percentage-point increase from 4% reaches 6%, not 4.08%. Apply every binding limit, not just the first cap you notice. A lifetime ceiling can be lower than the rate allowed by a periodic cap.
- Keep the prior effective rate in view at later adjustments. A periodic limit usually measures the allowed step from that prior rate under the stated note. The index can fall while the new formula result remains above a previously capped rate. Any carryover provision also needs its actual terms; an unused rate increase is not automatically unpaid interest.
- Recalculate the payment only after finding the permitted rate. For a standard fully amortizing reset, use the unpaid principal and remaining amortization term. Interest-only periods, payment caps and recasts can change that calculation. A cap on the rate is different from a dollar limit on the payment.
- Check the disclosures and the actual documents together. The Loan Estimate’s Adjustable Interest Rate table identifies the formula, change frequency and limits; projected payments address payment changes. APR is a broader cost disclosure, not a forecast of an ARM’s maximum rate.
- Compare the full obligation rather than assume a future escape. A lower starting rate does not establish the lowest lifetime cost. Selling or refinancing later depends on circumstances; neither is guaranteed. Use the examples to understand the terms, not to choose a product from its introductory payment alone.
| Term | What it does | Calculation cue |
|---|---|---|
| Index | Specified changing benchmark | Use the required observation or lookback |
| Margin | Contractual percentage-point add-on | Index + margin = fully indexed rate |
| Initial adjustment cap | Limits the first stated reset | Use the first-change base and limit |
| Periodic cap | Limits a later change | Use the prior rate specified by the note |
| Lifetime ceiling | Limits the overall rate | Use the stated initial-rate increase or absolute maximum |
| Floor | Sets a minimum | Do not reduce below it |
| Rounding | Moves the calculation to a specified increment | Follow the note’s order; not a universal increment |
| Fully amortizing reset | Recalculates scheduled principal and interest | Current unpaid balance, permitted rate, remaining term |
| Payment cap | Limits payment changes under its terms | Check whether unpaid interest can accumulate |
The distinctions that matter
| Distinction | How it works | What to notice |
|---|---|---|
| Fixed rate and ARM | Fixed describes an unchanged contract rate. An ARM permits scheduled formula changes; not every ARM changes immediately after closing. | What can change under the note? |
| Index and margin | The index is the specified benchmark. The contractual margin is added in percentage points and ordinarily stays fixed, subject to any valid replacement provisions. | Use the observed index and the agreed add-on. |
| Fully indexed rate and permitted reset | Index plus margin is the formula result. Rounding and contractual limits can produce a different charged rate. | Do not stop at the first addition. |
| Initial and periodic caps | The initial cap applies at the first adjustment when separately stated. A later periodic cap measures the permitted change from the specified prior rate. | First reset or a later step? |
| Lifetime increase cap and floor | A lifetime increase limit defines the overall ceiling under the note. A floor defines a minimum. Upward and downward provisions need not be identical. | Read the base, ceiling and minimum separately. |
| Rate cap and payment cap | A rate cap controls the interest rate. A payment cap controls a payment amount; under a loan permitting it, unpaid interest can be added to principal. | A limited payment need not cover all interest. |
| Interest-only and negative amortization | Paying all interest but no principal leaves the balance unchanged absent other events. Paying less than accruing interest can increase the balance if capitalization is permitted. | No principal reduction is different from balance growth. |
| Note rate and APR | The note rate governs contractual interest. APR reflects specified credit costs and assumptions. An ARM’s APR does not disclose its maximum possible rate. | A cost comparison is not a worst-case rate forecast. |
| Initial fixed period and full term | The initial period delays scheduled rate changes; the maturity states when the remaining obligation is due. | Five initial years need not mean a five-year loan. |
| Loan payment and total housing costs | Principal and interest are only part of the bill. Taxes, insurance and other items require separate attention. | A fixed note rate does not freeze escrow costs. |
Work through the facts
Index plus margin with no binding limit
The stipulated index is 3.80% and margin 2.25%. No cap, floor or rounding changes this calculation.
- Add percentage points: 3.80% + 2.25% = 6.05%.
- The question expressly removes other limiting conditions.
Answer: Permitted rate in this example: 6.05%.
The first-adjustment cap binds
An ARM starts at 4.00%. At its first reset the fully indexed rate is 7.25%. Its first increase limit is two percentage points. All other limits are nonbinding and no rounding applies.
- The first-reset ceiling is 4.00% + 2.00% = 6.00%.
- The formula’s 7.25% exceeds that ceiling.
Answer: The first reset is limited to 6.00%.
A later periodic cap binds
The previous effective rate is 6.00%. The next formula result is 8.40%. A one-percentage-point increase limit applies; the lifetime ceiling is above 7.00%, with no other binding term.
- The allowed step reaches 7.00%.
- The 8.40% formula result cannot all take effect now.
Answer: Permitted later rate: 7.00%.
The lifetime ceiling is lower
The original rate is 3.50%, with a lifetime increase limit of five percentage points. Other rules would permit 9.00%. No other term prevents the lower permitted result.
- Lifetime maximum: 3.50% + 5.00% = 8.50%.
- The lifetime ceiling blocks 9.00%.
Answer: The stated maximum is 8.50%.
A floor blocks part of a decline
The index is 0.75%, the margin 2.25%, and the absolute floor 3.50%. No downward periodic limit or other term binds.
- The formula gives 3.00%.
- The floor prevents a rate below 3.50%.
Answer: Permitted rate: 3.50%.
A falling index can still precede a higher charged rate
At the first reset a 7.25% formula result was capped at 6.00%. At the next reset the formula falls to 6.50%. A one-point upward periodic limit and all other terms permit 6.50%.
- The new formula is lower than the old 7.25%, but higher than the previously charged 6.00%.
- The new rate rises by 0.50 percentage point, within the stated one-point limit.
Answer: The rate can rise to 6.50% despite the lower formula result. This does not automatically add past unpaid interest.
Round only as instructed
An exercise gives index 4.04% and margin 2.25%, instructs rounding their sum to the nearest 0.125 percentage point, and states that no cap or floor binds.
- Unrounded result: 6.29%.
- 6.25% is nearer than the adjacent 6.375% step.
Answer: The rounded permitted rate is 6.25%, not an assumed universal rounding rule.
Fixed rate, higher escrow
Scheduled fixed-rate principal and interest is $1,200. The monthly tax and insurance escrow amount rises from $400 to $475. No other items change.
- Old total: $1,600; new total: $1,675.
- The $75 increase comes from escrow, not a change to the note rate.
Answer: The loan can remain fixed rate while the total rises to $1,675.
A capped payment does not cover the interest
A hypothetical contract permits unpaid interest to be capitalized. Accruing interest is $1,200, the allowed payment is $1,000, and there are no fees, principal payments or other balance changes.
- Unpaid interest is $200.
- If added to a $200,000 balance under the stated terms, the new balance is $200,200.
Answer: The payment limit does not prevent negative amortization in this stipulated product.
A normal reset uses the remaining term
At a fully amortizing reset, the unpaid principal is $200,000, the permitted rate is 6% and 25 years remain. Monthly payments begin one month later; there are no fees or other payment features.
- The remaining term is 300 months, not a new 360-month schedule.
- A standard monthly amortization calculation gives principal and interest of about $1,288.60, before taxes and insurance.
Answer: Use the current balance and remaining term; do not restart a 30-year amortization without an actual loan provision.
Two caps apply at once
The starting rate was 4.00%. At the first change, the formula is 8.00%, the initial upward limit is two points and the lifetime upward limit is 1.50 points from the original rate. No floor or rounding binds.
- The initial-change ceiling is 6.00%, but the lifetime ceiling is 5.50%.
- Both apply, so the lower ceiling controls the 8.00% formula.
Answer: The permitted first rate is 5.50%. The example’s cap amounts are fictional, not a claim about a standard product.
A downward step can be limited too
The prior rate is 7.00%, the formula falls to 4.50%, the absolute floor is 3.00% and this later change may decrease by at most one percentage point. No other term binds.
- The one-step lower bound is 6.00%, above the absolute floor.
- The formula cannot fall straight to 4.50% at this adjustment.
Answer: The permitted new rate is 6.00%; a floor is not the only possible downward restriction.
Mistakes to avoid
- Fixed rate means every part of my payment stays fixed. Separate note interest and scheduled principal from changing escrow and other costs.
- Index alone is the new ARM rate. Add the margin, then apply the required rounding and limits.
- The fully indexed result always takes effect immediately. A cap or floor can prevent that result at the current adjustment.
- Every cap is measured from the initial rate. A later periodic cap usually refers to the prior rate under the stated note; the lifetime ceiling uses its own base.
- A two-percent cap means multiplying a 4% rate by 1.02. A two-percentage-point increase reaches 6%, not 4.08%.
- A falling index guarantees a lower charged rate. Compare the new formula with the previously capped rate and all downward limits.
- A payment cap prevents balance growth. Check whether the payment covers interest and whether unpaid interest may be capitalized.
- A 5/6m ARM adjusts every six years. The common notation means six-month adjustments after five initial years.
- APR shows the worst possible ARM rate. It is a cost disclosure with assumptions, not the maximum contractual rate.
- I can always refinance before the reset. Later qualification, property value and available terms are uncertain.
Check your understanding
These are original teaching questions, not recalled or predicted PSI questions. Answer first, then explain why the other choices fail.
1. What defines a fixed-rate mortgage?
- It has no other payment features
- It must have a five-year maturity
- Its contract interest rate remains unchanged
- Its taxes can never rise
Show answer and explanation
Answer: C. Its contract interest rate remains unchanged
Fixed rate describes the note interest rate. Typical fully amortizing scheduled principal and interest can stay level, while escrow or other features still need review.
2. The index is 4.10% and the margin 2.25%. Before rounding and limits, what is the fully indexed rate?
- 2.25%
- 4.10%
- 1.85%
- 6.35%
Show answer and explanation
Answer: D. 6.35%
Add percentage points: 4.10 + 2.25 = 6.35. The question asks for the formula result, not whether a contractual cap permits it.
3. Which part is ordinarily the market-based moving component?
- The contractual margin
- The index
- The original loan principal
- The property’s asking price
Show answer and explanation
Answer: B. The index
Use the benchmark and observation specified by the note. The margin is ordinarily the agreed percentage-point add-on, with any replacement provisions considered separately.
4. An initial 4.00% rate has a two-percentage-point first increase limit. The formula is 7.25%; no other term binds. What rate is permitted?
- 6.00%
- 4.08%
- 9.25%
- 7.25%
Show answer and explanation
Answer: A. 6.00%
The first-change ceiling is 4.00% + 2.00% = 6.00%. Percentage points are added, not multiplied as a two-percent change to the original rate.
5. The prior rate is 6.00%, the new formula 8.40%, and the later increase cap one percentage point. No other term binds. What is the rate?
- 8.40%
- 7.00%
- 9.40%
- 6.06%
Show answer and explanation
Answer: B. 7.00%
The later step is measured from the stipulated prior rate: 6.00% + 1.00% = 7.00%. It is lower than the formula result.
6. A loan began at 3.50% with a five-percentage-point lifetime increase cap. What is that stated ceiling?
- 5.00%
- 3.675%
- 8.50%
- 9.00%
Show answer and explanation
Answer: C. 8.50%
Add the stated lifetime increase to its specified initial-rate base: 3.50% + 5.00% = 8.50%. Other limits may restrict a particular reset further.
7. The formula gives 3.00%, the floor is 3.50%, and all other terms permit that floor. What is the effective reset?
- 3.00%
- 3.50%
- 0.50%
- 6.50%
Show answer and explanation
Answer: B. 3.50%
The floor is the minimum. A lower formula result does not overcome the expressly stated 3.50% minimum.
8. What does common 5/6m ARM notation describe?
- Six initial years followed by five-month changes
- A five-month loan with six-year changes
- A five-year maturity with six payments
- Five initial fixed years followed by six-month rate adjustments
Show answer and explanation
Answer: D. Five initial fixed years followed by six-month rate adjustments
Read the actual product documents, but in this common notation 5 refers to the initial years and 6m to the later six-month adjustment period, not maturity.
9. The prior charged rate is 6.00% after a cap. The new formula falls from 7.25% to 6.50%, and all terms permit 6.50%. Which is possible?
- The margin must have become zero
- The loan must become fixed rate
- The rate must fall below 6.00%
- The charged rate rises to 6.50% despite a lower formula result
Show answer and explanation
Answer: D. The charged rate rises to 6.50% despite a lower formula result
Compare with the previously charged rate, not only with the old uncapped formula. The new 6.50% remains above the prior effective 6.00%.
10. The stipulated calculation is 6.29%, rounded to the nearest 0.125 percentage point with no binding limit. What is the result?
- 6.00%
- 6.25%
- 6.375%
- 6.50%
Show answer and explanation
Answer: B. 6.25%
The adjacent steps are 6.25% and 6.375%. Distances are 0.04 and 0.085 percentage point, so 6.25% is closer.
11. What does a payment cap necessarily establish?
- That taxes can never rise
- That the balance can never increase
- That interest can never exceed the payment
- A limit on payment changes under its stated terms, not automatic payment of all interest
Show answer and explanation
Answer: D. A limit on payment changes under its stated terms, not automatic payment of all interest
The payment and the accruing interest are different quantities. Balance treatment depends on the actual contract; a payment cap is not a universal rate cap.
12. A permitted $1,000 payment covers only part of $1,200 interest, with capitalization expressly allowed and no other changes. What is added to the balance?
- $1,200
- $200
- $2,200
- $1,000
Show answer and explanation
Answer: B. $200
The unpaid portion is $1,200 - $1,000 = $200. The stipulated contract allows that unpaid interest to be added to principal.
13. What is true of an ARM’s disclosed APR?
- It guarantees refinancing eligibility
- It is always the maximum lifetime rate
- It is the margin alone
- It is a broader cost disclosure and does not show the maximum possible ARM rate
Show answer and explanation
Answer: D. It is a broader cost disclosure and does not show the maximum possible ARM rate
APR uses specified costs and assumptions. Review the note’s maximum rate and payment exposure separately instead of treating APR as a worst-case forecast.
14. Fixed-rate principal and interest is $1,200 and escrow rises from $400 to $475. With nothing else changed, what is the new total?
- $1,600
- $1,200
- $1,275
- $1,675
Show answer and explanation
Answer: D. $1,675
$1,200 + $475 = $1,675. The increase in total does not, by itself, establish that the note rate changed.
15. At a standard fully amortizing reset, which inputs belong in the new scheduled-payment calculation?
- Current unpaid principal, permitted new rate and remaining amortization term
- APR and original asking price
- Original principal and an automatic new 30-year term
- Property value and the seller’s mortgage balance
Show answer and explanation
Answer: A. Current unpaid principal, permitted new rate and remaining amortization term
Determine the contractually permitted rate first, then use the current balance and remaining term. Special interest-only or payment-cap provisions require their own treatment.
16. A borrower plans to refinance before an ARM reset. Which statement is sound?
- An initial low payment permanently fixes affordability
- Later refinancing depends on qualification and available terms
- Refinancing is guaranteed by choosing an ARM
- A home value decline always reduces the note rate
Show answer and explanation
Answer: B. Later refinancing depends on qualification and available terms
A future refinancing or sale is not guaranteed. Qualification, property value and available terms can change before the adjustment.
17. A borrower pays all scheduled interest but no principal during an interest-only phase, with no fees or other changes. What happens to principal?
- It is fully repaid
- It remains unchanged
- It becomes the property’s assessed value
- It necessarily grows
Show answer and explanation
Answer: B. It remains unchanged
Paying all accruing interest avoids unpaid-interest growth under these facts, but it does not reduce principal. That differs from negative amortization.
18. Which item should be checked instead of assuming every ARM uses the same index observation?
- The seller’s preferred moving date
- The home’s listing photograph
- Only the year of construction
- The note’s index source and lookback provision
Show answer and explanation
Answer: D. The note’s index source and lookback provision
The relevant benchmark value is determined by the contract’s observation rule. Today’s quoted value need not be the index used for a particular adjustment.
19. At a first reset the formula is 8.00%. A 4.00% starting rate has a two-point initial increase cap and 1.50-point lifetime increase cap. No other term binds. What is permitted?
- 5.50%
- 8.00%
- 6.00%
- 9.50%
Show answer and explanation
Answer: A. 5.50%
The initial ceiling is 6.00%, while the lifetime ceiling is 5.50%. Both apply, so the lower 5.50% ceiling controls. These stipulated amounts are not a standard-product claim.
20. The prior rate is 7.00%, the formula 4.50%, the floor 3.00% and the stated later decrease limit one percentage point. With no other binding term, what rate applies?
- 8.00%
- 3.00%
- 6.00%
- 4.50%
Show answer and explanation
Answer: C. 6.00%
The periodic downward limit permits only a one-point decrease from 7.00%, reaching 6.00%. It is above the absolute floor and prevents the full formula decline at this adjustment.
Common questions
What is the main difference between a fixed-rate mortgage and an ARM?
A fixed rate stays unchanged under the loan’s terms. An ARM permits rate changes on its schedule. Compare that rate behavior separately from the loan’s maturity, amortization and other payment features.
Can a fixed-rate mortgage payment increase?
The total can rise when taxes, insurance, escrow or other charges change. On a typical fully amortizing fixed-rate schedule, principal and interest remain level. Check any special payment feature rather than assume a fixed rate fixes every dollar.
What are the index and margin?
The index is the benchmark identified by the note. The margin is the contractual percentage-point add-on. Index plus margin gives the fully indexed rate before applicable rounding and limits. Check the specified observation date and any valid replacement provisions.
Does a lower index guarantee a lower ARM rate?
No. A floor or downward-change limit may restrict a decrease. Also compare with the previously charged rate: a lower new formula can still exceed an older capped rate. Carryover provisions require their own terms.
What does 5/1 or 5/6m mean?
Commonly, each starts with five fixed years. The later adjustment is annual for 5/1 and every six months for 5/6m. Those labels do not establish the full maturity or every cap. Read the rate table and note.
How do initial, periodic and lifetime caps differ?
The initial cap limits the first stated adjustment; the periodic cap limits later steps; the lifetime rule supplies an overall limit using its stated base. Check increases and decreases separately. A floor can establish an absolute minimum.
Is a two-percent adjustment cap the same as multiplying the old rate by 1.02?
In the stated cap examples, two means two percentage points. A 4% rate plus two points is 6%. Multiplying 4% by 1.02 gives 4.08%, which is not that two-point cap calculation.
What if more than one cap or floor applies?
Apply them together. An initial or periodic limit does not override a tighter lifetime ceiling, and an absolute floor does not erase a tighter downward step limit. Use the note’s required sequence and all stated conditions. Do not assume the first cap mentioned decides the answer.
Are rate caps and payment caps the same?
No. A rate cap limits the rate; a payment cap limits a payment change. If a contract allows unpaid interest to be capitalized, a payment below the interest due can increase principal. Not every ARM has that feature.
How is the new ARM payment calculated?
For a standard fully amortizing reset, determine the permitted rate and use the unpaid balance with the remaining term. Special payment features need separate treatment. Taxes and insurance remain outside that principal-and-interest calculation.
Does every ARM use SOFR and the same rounding rule?
No. The cited Form 3441 is an example of a 30-day Average SOFR note with its own observation, rounding and replacement terms. Other notes can differ. Use the documents or the exact instructions in an exam problem.
Can a margin ever change?
It ordinarily stays fixed, but read the replacement provisions. Form 3441 expressly allows a replacement margin in specified replacement-index circumstances. That is not permission for a lender to reprice the margin whenever it chooses.
Is APR the maximum rate I could pay?
No. APR reflects specified credit costs and assumptions. CFPB specifically cautions that an ARM’s APR does not reflect its maximum interest rate. Compare the note rate, fees, caps and payment exposure separately.
Which disclosures help explain an ARM?
The Loan Estimate’s Adjustable Interest Rate table and projected payments help identify formula, timing, limits and payment behavior. Covered variable-rate loans also have program-disclosure requirements under Regulation Z. Check the applicable coverage and timing rules rather than assume every loan uses an identical notice schedule.
Will a lower starting rate make an ARM cheaper overall?
Not necessarily. Future adjustments, fees, loan duration and later options affect the result. This guide uses fictional rates to teach the terms; it does not predict future rates or determine the best loan for an individual borrower.
Are these official exam questions?
No. They are original educational examples tied to the public Financing outline. Use unfamiliar scenarios to test the reasoning. A practice score here is not a validated forecast of your PSI result.
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Official sources and scope
The identified CFPB guidance, published CHARM booklet, selected Regulation Z passages and Form 3441 were read October 26, 2026. The form is a specific example, not the terms of every ARM. CHARM’s sample disclosures are not a substitute for the applicable rule or an executed note. No current index value, loan quote, future refinancing approval or individual suitability conclusion is supplied.
- PSI June 24, 2026: National IV.B.3 ARM loans
- CFPB: fixed-rate and ARM comparison
- CFPB: ARM index, margin and fully indexed rate
- CFPB: initial, subsequent and lifetime rate caps
- CFPB CHARM booklet: notation and document map
- CFPB: negative amortization
- CFPB: reasons a monthly payment changes
- CFPB: mortgage note rate and APR
- CFPB: monthly payment calculation and ARM reset
- CFPB: interest-only phase and later obligations
- Regulation Z1026.19(b): covered variable-rate program disclosures
- Fannie Mae/Freddie Mac Form3441: SOFR note example
This is exam preparation, not advice for a specific transaction. State law and the applicable facts control. Our editorial and corrections process explains how to report an issue.