The 36-month trap: why 'monthly' phone prices never end at 24

How 36 months became the default

As flagship prices crossed $1,000, carriers stretched device installment plans to 36 months to keep the advertised monthly number low. The promo credit stream follows the financing: $1,000 over 36 months is about $27.78/month, not a discount at the register.

The quiet consequence: at month 24 — when you used to own the phone — a 36-month plan still has roughly a third of the device balance left AND roughly a third of the credits un-posted. Upgrading 'on schedule' means unwinding both.

Three costs people forget to stack

• Un-posted credits: upgrade at month 24 and you forfeit about a third of the promised credit (in our seeded $1,000 example, roughly $333).
• Remaining device balance: the installments don't stop because you want a new phone; the balance is due or trades in at less than you owe.
• Depreciation cliff: resale value drops fastest in months 12–24. Selling at 36 months recovers far less than the credit math assumes — our resale curve seeds show the 24→36 month drop explicitly.

A worked example (seeded values)

Take a $1,099 flagship with a $1,000/36-month credit on a top-tier plan. Stay the full 36 months: the phone effectively costs you the tax plus whatever your plan delta was. Upgrade at month 24: you've eaten the tax, lost ~$333 of credits, still owe ~$366 of device balance, and the 'free' phone becomes roughly a $700+ phone. Same promo, same phone — the ending changed the price by more than half.

This is why our report shows every path at both 24 and 36 months with the lock, the forfeit schedule, and the resale curve visible — the calendar is part of the price.

What to do about it

• Decide your holding period BEFORE choosing a path. If you upgrade every 2 years, the lease and carrier-credit paths punish you on purpose.
• Model both horizons: our sandbox shows 24 vs 36 months for the same inputs.
• If you already took a 36-month promo, a monthly credit ledger turns a silent forfeit into a documented dispute.

Sources & confidence

As of 2026-09: 36-month amortization for carrier flagships is standard practice (confidence: high); the exact credit split per promo is carrier-specific (confidence: low — official promo pages govern: https://www.t-mobile.com/offers, https://www.att.com/deals/, https://www.verizon.com/deals/phones/). Numbers in the worked example are seeded example values, not quotes. Not financial advice.