Payments & EMI

Trilobyte uses an Equated Monthly Instalment (EMI) model for loan repayments. Each payment is a fixed amount calculated at disbursement, covering both principal and interest.

EMI Calculation

The EMI is calculated using the standard amortisation formula:

$$EMI = P \times \frac{r(1+r)^n}{(1+r)^n - 1}$$

Where:

• $P$ = Principal (loan amount)

• $r$ = Monthly interest rate (annual rate ÷ 12)

• $n$ = Number of monthly payments (loan term)

All math is integer-only — Soroban has no floating-point support. Trilobyte uses 10¹² internal precision scaling and ceiling-rounds the final EMI to ensure the borrower always repays at least the full amount owed.

Payment Split

Each payment is split into two pools based on the vault's split ratio:

Pool	Purpose	Accessible By
EMI Pool	Investor yield — proportional to split ratio (e.g. 80%)	Investors via claim_yield
Cash Pool	Borrower operating capital — remainder (e.g. 20%)	Borrower via withdraw_cash

For example, with a split ratio of 80, a gross payment of 10,000 USDC splits:

• 8,000 USDC → EMI pool (investor yield)

• 2,000 USDC → Cash pool — from which the 0.5% protocol fee is taken (→ ~1,950 USDC to the borrower)

Because only the EMI share repays the loan, the borrower grosses up the payment so that split_ratio% of it covers one investor instalment — i.e. gross = ceil(EMI × 100 / split_ratio). The contract exposes get_required_payment / get_current_period_payment for the exact amount due.

Payment Schedule

• Payments are due every 30 days (30/360 day-count convention)

• The first payment is due 30 days after disbursement

• Each payment advances the next_due date by 30 days

• The loan term sets the EMI schedule, but the loan completes when the outstanding balance reaches zero — not on a fixed payment count

Principal Amortisation

Each EMI payment contains both an interest component and a principal component:

$$\text{interest} = \text{outstanding} \times \frac{\text{annual\_rate}}{12}$$

$$\text{principal} = \text{EMI} - \text{interest}$$

The outstanding principal decreases with each payment. Early payments are interest-heavy, while later payments are principal-heavy — standard amortisation behaviour.

Protocol Fee

A 0.5% protocol fee applies to every repayment — but after the split, and only from the borrower's cash share. Investor (EMI) yield is never reduced by the fee:

1. Gross payment received (e.g. 10,000 USDC)

2. Split by ratio first (e.g. 8,000 → EMI pool, 2,000 → cash share)

3. The 0.5% fee (50 USDC) is taken from the cash share → 1,950 to the cash pool, 50 to the treasury

See Fees for the full model (including the fee clamp).

Yield Claiming

Investors claim their share of the EMI pool proportionally:

$$\text{claimable} = \frac{\text{balance}}{\text{total\_supply}} \times \text{emi\_pool} - \text{already\_claimed}$$

• balance = Investor's debt token balance

• total_supply = Total debt token supply

• emi_pool = Total accumulated EMI pool

• already_claimed = Amount the investor has already claimed

Claims can be made at any time during the Active or FullyRepaid phases.

Token Precision

All amounts use 7 decimal places (Stellar standard). For example:

• 1 USDC = 10_000_000 (10⁷)

• 0.5% fee = 50_000 in 7-decimal format