US phone buying guide
US carrier bill credits: calculate the real discount
Model monthly credits, plan requirements, taxes, trade-ins, and the cost of leaving early.
A free-phone offer is a financing schedule
Most US carrier promotions finance the device at its ordinary installment price and apply a separate credit each month. The advertised discount is earned gradually; it is not the same as a cash reduction on purchase day. Record the financed amount, term, monthly device charge, monthly credit, sales tax due at purchase, activation fee, and required plan before comparing offers.
A 36-month promotion produces its full stated value only if all 36 credits post. A useful analysis therefore shows both the full-term outcome and an early-exit outcome instead of treating the maximum credit as guaranteed cash.
Calculate the service-plan difference
A promotion can require a premium unlimited plan. Compare that plan with the least expensive plan you would independently choose, then multiply the monthly difference by the promotional term. A $15 monthly plan premium costs $540 over 36 months and can consume much of a headline device discount.
For family plans, calculate the incremental cost of the affected line rather than dividing the entire account bill mechanically. Taxes, surcharges, autopay rules, and multi-line discounts vary, so label every assumption and retain the carrier source date.
Model leaving before the credits finish
At a chosen exit month, add the unpaid device balance and subtract only credits already received. Confirm whether payoff, upgrade, plan change, line cancellation, or account transfer stops future credits; carrier terms differ and can change. Do not assume that paying off a phone preserves the remaining promotion.
The relevant comparison is the total phone-and-service cost through the exit date, not merely the remaining phone balance. This reveals whether flexibility is worth more than the nominal maximum discount.
Treat trade-in value separately
Trade-in credits depend on an eligible model, condition, timely shipment, account status, and successful inspection. Record the device surrendered and a reasonable alternative resale value. The promotion's incremental trade-in benefit is the carrier credit minus the value you gave up—not the entire promotional credit.
Photograph the trade-in condition, record identifiers, retain tracking, and save the promotion terms. These operational steps do not change the arithmetic, but they reduce the risk that an expected credit becomes a disputed one.
Decision rule
Use carrier credits when the qualifying service already fits your needs, the ownership term is realistic, and the exit scenario remains acceptable. Prefer an unlocked cash purchase when plan flexibility, international use, resale timing, or predictable cost matters more.
Phone Price Tracker's calculator is an educational model, not a carrier quote. Final eligibility, taxes, credit timing, and cancellation consequences must be confirmed with the carrier before purchase.
Published by Phone Price Tracker · Editorially reviewed July 31, 2026