Updated August 31, 2026
In this guide
Where adjustment enters
In a simplified model, the index updates the balance before the rest of the calculation:
TR is therefore not simply added to interest. It changes the base on which interest and amortization are processed.
Official reference
The build reads official SGS 226 observations with start date, end date and rate, then selects the highest rate in a rolling twelve-month window. The simulator repeats it monthly as a conservative estimate and labels the selected period.
With and without TR
Both variants keep amount, term, SAC and the BCB median for TR-indexed mortgages. Only adjustment changes.
BCB reference rate: 2026-07, median of 13 institutions.
TR reference: 0.1760% monthly, observation dated October 7, 2025, repeated only as an estimate.
Parameters used
- Financed amount
- R$300,000.00
- Term
- 360 months
- Interest rate
- 12.0149% effective per year
- System
- SAC
- Monthly adjustment
- 0.1760%
- Extra amortization
- —
Calculated results
| Scenario | Without TR | With estimated fixed TR |
|---|---|---|
| First payment | R$3,683.33 | R$3,689.82 |
| Last payment | R$842.46 | R$1,584.36 |
| Total interest | R$514,427.03 | R$643,356.93 |
| Total paid | R$814,427.03 | R$1,062,337.81 |
| Effective term | 360 months | 360 months |
| Accumulated adjustment | R$0.00 | R$118,980.88 |
Selected installments
| Payment no. | Payment | Interest | Amortization | Closing balance |
|---|---|---|---|---|
| 1 | R$3,689.82 | R$2,855.02 | R$834.80 | R$299,693.20 |
| 12 | R$3,672.94 | R$2,821.84 | R$851.10 | R$296,184.44 |
| 60 | R$3,574.13 | R$2,648.07 | R$926.06 | R$277,818.52 |
| 180 | R$3,110.08 | R$1,966.46 | R$1,143.62 | R$205,851.88 |
| 360 | R$1,584.36 | R$14.91 | R$1,569.45 | R$0.00 |
The accumulated path is not a forecast. Actual TR varies and each contract determines how observations reach the balance.
What may differ in a contract
- Contracts may apply TR by anniversary and their own date rules; verify the clause and statement.
- Adjustment may occur before interest and amortization, changing each balance step.
Limits of this analysis
- The scenario repeats the highest observation in the annual window as a fixed monthly rate; this is not a TR forecast.
- It does not reproduce anniversaries, lags, pro rata rules or future changes.
Sources and review
- Central Bank of Brazil — TR series SGS 226 · July 27, 2026
- Central Bank of Brazil — Citizen Calculator · July 27, 2026