Biweekly, semi-monthly and accelerated payments
Separate payment timing from an increased annual payment budget.
Count dates, not names
Every fourteen days is not twice a month. A dated biweekly series moves through the calendar. Two fixed monthly dates generate a different series. Some calendar years contain twenty-seven biweekly payment dates.
Half-payment biweekly adds money
Half the monthly reference payment made twenty-six times is thirteen full reference payments. Part of the acceleration comes from paying more, not simply changing dates. Our normalized mode scales by twelve divided by twenty-six, but the actual calendar and final capped payment can still change the horizon’s total.
Keep the interest convention identical
Our dated comparison uses simple daily Actual/365 in every alternative. It includes the principal and unpaid accrued interest at the comparison date. The monthly-annuity reference amount may leave a small residual under daily accrual; the residual remains visible.
Servicers may work differently
A lender may hold half payments until a full contractual payment arrives or use monthly interest. Check the agreement. The illustrative daily schedule does not claim to reproduce those rules.