Biweekly payment and "DIY extra 1/12" produce nearly identical results: both add one extra full payment per year to principal. The question is which way fits your cash flow and avoids servicer fees.
Worked example: $350,000 loan, 7%, 30-year, $2,328/mo P&I. Biweekly = $1,164 every 2 weeks (26 payments = $30,264/year = 13 monthly). DIY extra = $2,328 + $194 extra principal = $2,522/mo ($30,264/year). Same payoff impact: ~5 years 10 months off the loan, ~$88,500 interest saved.
When biweekly wins
- You're paid biweekly and it matches your cash flow
- Your servicer offers biweekly enrollment free
- You need automatic discipline — can't trust yourself to send the extra
When DIY 1/12 extra wins
- Your servicer charges a biweekly enrollment fee ($4-$10/payment is common and predatory)
- You want the flexibility to skip the extra in a tight month
- You prefer the simplicity of one monthly payment
Most homeowners should pick the DIY route. Same math, zero fees, total flexibility.
How the servicer actually applies biweekly
Many servicers do NOT credit each half-payment immediately. They hold half-payments in suspense and apply both halves on the 1st of the month. If that's your servicer, biweekly is functionally identical to DIY 1/12 extra — and you might as well DIY it to avoid any possible fee. Call your servicer to confirm.