Margin interest is the financing cost charged on money borrowed from a broker in a margin account.
Margin interest is the financing cost a broker charges on money borrowed in a margin account. It accrues on the margin debit balance and reduces the net result of any trade financed with broker credit.
Margin interest matters because leverage has a carrying cost. A trade can have a favorable price move and still produce a weak result after interest, commissions, taxes, and borrow-related costs.
Many brokers display an annualized margin rate. A simplified estimate is:
1interest cost = debit balance x annual rate x days borrowed / day-count basis
For example, if an investor borrows $10,000 at an 8% annualized rate for 30 days, a rough 365-day estimate is about $65.75 before compounding, billing conventions, commissions, and taxes. The actual account charge depends on broker terms.
| Record | What to check |
|---|---|
| Broker rate schedule | Annualized rate tiers and benchmark references |
| Daily account activity | Debit balance and accrual timing |
| Monthly statement | Posted interest charges |
| Trade review | Whether expected return still compensates for financing cost |
| Tax records | Whether any deduction or limitation applies to the investor’s situation |