Siwoo Park
In the Smart Choice example (a phone with a launch price of KRW 1,000,000 and a plan costing KRW 55,000 per month), taking the public subsidy gives a lower 24-month total. If you receive a public subsidy of KRW 530,000, the actual purchase price of the phone is KRW 470,000, plus a monthly phone bill of KRW 55,000. If you choose the selective plan discount instead of the subsidy (assumed to have the same structure as buying an unlocked phone at the launch price and adding a carrier selective plan discount), the actual purchase price of the phone is KRW 1,000,000, plus a monthly phone bill of KRW 41,250. [1][1][1] You can compare the 24-month totals of the two options directly with the formulas in the table below. Because the selective plan discount cuts only 25% of the monthly bill, the phone discount is larger than the bill discount in this plan range. [1]
The unlocked phone gains its advantage elsewhere. The 25% bill discount is available only to subscribers of the three mobile carriers (SKT, KT, LG U+), and users of MVNOs (알뜰폰 providers) are excluded. [2] So when you pair an unlocked phone with an MVNO, the total cost reverses only if the MVNO's monthly bill itself is low, not because of a discount rate. The reference date is November 2026, and all calculations below use the same formulas with only the numbers changed.
24-Month Total Cost Formula: Phone Price + Total Phone Bills
Even when the purchase methods differ, you can use one standard for comparison. A device subsidy (phone discount) is a one-time discount on the phone price that assumes a 2-year contract, and the selective plan discount is a phone bill discount that takes 25% off the plan's monthly fee every month during the contract period. [1][1][1] A 2-year contract is 24 months, so multiply the monthly bill by 24 and add the phone price. Fill in the blanks in the formulas below with your own numbers.
- Carrier public subsidy: Launch price − public subsidy − additional subsidy + (monthly fee × 24)
- Carrier selective plan discount: Launch price + {(monthly fee − 25% discount on the monthly fee) × 24}
- Unlocked phone + MVNO: Unlocked phone purchase price + installment interest + (MVNO monthly bill × 24)
- Unlocked phone + carrier selective plan discount: Unlocked phone purchase price + installment interest + {(monthly fee − 25% discount on the monthly fee) × 24}
An unlocked phone is usually bought by paying the full price at once, without a contract. [3] If a lump-sum payment is a burden, you can use seller benefits such as card payment-date discounts or long-term interest-free installments. [3] If you choose an installment plan that is not interest-free, the installment interest term in the formula is not 0, so you must fill it in.
Public Subsidy vs 25% Selective Plan Discount: Calculation with a KRW 1,000,000 Launch Price
You can choose only 1 of the public subsidy and the selective plan discount, so compare them before you buy. [1] You need to pick the better of the two benefits, so compare them by the 24-month total. [1] Converting the example of buying a phone with a launch price of KRW 1,000,000 on a plan of KRW 55,000 per month to the same standard gives the following. The values exclude the additional subsidy (from dealers and retailers).
| Category | Phone price | Monthly phone bill | 24-month total (calculated) |
|---|---|---|---|
| Device subsidy (public subsidy) chosen | Actual phone purchase price KRW 470,000 [1] | Monthly phone bill KRW 55,000 [1] | KRW 470,000 + (KRW 55,000 × 24 months) |
| Selective plan discount (2 years) chosen | Actual phone purchase price KRW 1,000,000 [1] | 25% of the monthly fee, KRW 13,750, is discounted, so the monthly phone bill is KRW 41,250 [1][1] | KRW 1,000,000 + (KRW 41,250 × 24 months) |
Choosing the public subsidy means receiving a phone discount of KRW 530,000 at once. [1] The selective plan discount means receiving a total selective plan discount (2 years) of KRW 330,000 in installments of KRW 13,750 per month. [1] Comparing the subsidy of KRW 530,000 with the total selective plan discount of KRW 330,000, the public subsidy gives the larger discount in this example.
This result can flip depending on the plan and the phone. This is because the device subsidy varies by phone and plan. [1] With a combination of a high monthly fee and a small public subsidy, the 25% discount on the monthly bill can be larger. Right before you buy, check the public subsidy for that phone and recalculate by changing only the numbers in the table above.
When Does the Total Cost Reverse for an Unlocked Phone + MVNO?
If you sign up with a phone that did not receive a device discount subsidy, such as an unlocked phone bought directly from a domestic or overseas retailer, you can receive a bill discount equivalent to the public subsidy discount instead. [2] Using the selective plan discount system, you can get a 25% discount on your mobile phone bill. [2] As seen above, an MVNO does not receive this 25% bill discount. [2] Looking at the three combinations, the comparison is as follows.
| Combination | Phone discount | 25% bill discount | Items to check in the 24-month total |
|---|---|---|---|
| Carrier + public subsidy | Public subsidy applied [1] | Cannot be combined with the selective plan discount [1] | Actual purchase price + total monthly fees |
| Unlocked phone + carrier selective plan discount | Seller card discounts and coupons available [4] | 25% discount when subscribing to one of the 3 mobile carriers [2][2] | Unlocked phone purchase price + total discounted monthly bills |
| Unlocked phone + MVNO | Seller card discounts and coupons available [4] | MVNO users are excluded from the 25% bill discount [2] | Unlocked phone purchase price + total MVNO monthly bills |
You should also factor in that an unlocked phone can receive both a phone discount and a bill discount at the same time. [4] Card discounts and coupon discounts offered by the seller can be used on both the phone side and the bill side. [4] These discount amounts may differ by seller, so it is more accurate to subtract them in advance from the unlocked phone purchase price in the formula.
The reversal condition comes down to one inequality below.
- If the value of the unlocked phone + MVNO formula is smaller than the value of the carrier public subsidy formula, the unlocked phone + MVNO is more advantageous.
- If the comparison target is the selective plan discount, just replace the comparison value with the value of the carrier selective plan discount formula.
- In the MVNO monthly bill field, do not apply the 25% discount. Enter the amount on the rate table as it is. [2]
For a phone with a large carrier public subsidy, as in the example above, the value on the right side gets smaller, so the MVNO's monthly bill must be much lower for the total to reverse. Conversely, for a phone with a small public subsidy, the value on the right side of the inequality above gets larger, so the unlocked phone has more room to be advantageous. An unlocked phone is also bought without a contract, so there is no contract period or penalty burden. [3] You can read more about the MVNO number portability procedure and the difference from the 25% bill discount in MVNO number portability standards and the 25% selective plan discount compared.
Dealer Additional Subsidy and Switching Subsidy: Variables That Change the Total
In the carrier-side calculation, the phone discount structure differs by subscription type. Of the two branches below, enter the one that fits your situation in the subsidy field of the formula.
- New subscription or device change: If you subscribe as a new customer or change your phone while staying with your current carrier, the public subsidy provided by the carrier applies. [1]
- Number portability: If you change your phone and also change carriers, a switching subsidy is added to the public subsidy. [1]
Distribution networks such as retailers and dealers can give an additional subsidy on top of the carrier subsidy. The limit is up to 15% of the public subsidy and up to 15% of the switching subsidy. [1][1] The public subsidy total in the table above excludes the additional subsidy, so if you receive an additional subsidy at an actual store, the public subsidy total goes down by that amount. An additional subsidy exists only when the distribution network provides it, so enter the actual amount written on your quote in the additional subsidy field of the formula.
Check Before Buying an Unlocked Phone: IMEI, Carrier Compatibility, SIM
Since the device self-purchase system (단말기 자급제) was introduced, you can buy a phone not only from mobile carriers but also from manufacturers, large supermarkets and online shopping malls, and then sign up for service. [4] Even if the total cost is low, it means nothing if the phone cannot be activated, so check in the order below before paying.
- In the list of phones usable with the service of the mobile carrier you plan to join (including MVNOs), check that the model is available. [4]
- If you bought the phone from a general retailer other than a mobile carrier, note the device identification number (IMEI). [4]
- On an iPhone, you can see the IMEI in
Settings > General > About, and on a Galaxy, inSettings > About phone > Status information. Menu names may differ slightly by version. - Check whether you can insert your existing SIM and use it right away. [4]
- If you plan to use an eSIM (embedded SIM), first check in the official guides of the manufacturer and the carrier whether the model supports it and how activation works.
Cautions When Canceling During a Contract or Re-enrolling After 24 Months
If you cancel an existing contract and then sign up again with the 25% selective plan discount, a penalty and a discount refund will apply. [3] If you want to switch to an unlocked phone while the contract on your current phone remains, a penalty or discount refund may arise on cancellation, so check the amount with your carrier and add it to the 24-month total formula. Both the public subsidy and the selective plan discount are benefits that assume a contract period. [1][1]
After the contract ends, the situation is different. For a phone whose contract has expired because 24 months have passed since activation, you can re-enroll in the selective plan discount. [2] The selective plan discount is a bill discount benefit you can receive instead of the phone's public subsidy discount. [2] Apply in the order below.
- Check that the contract has expired, 24 months after the activation date. [2]
- Visit an agency or sales office of the mobile carrier you currently use. [2]
- Bring your ID and apply for the selective plan discount. [2]
- After re-enrolling, check on your bill that the 25% discount on the monthly fee has been applied. [2]
Frequently Asked Questions
Q1. Can I get both the selective plan discount and the public subsidy?
You can choose only 1 of the two. [1] The selective plan discount is a bill discount you receive instead of the public subsidy discount, so compare the totals as in the table above before you buy and then choose. [2]
Q2. Can I get the 25% selective plan discount if I go with an MVNO?
You cannot. For an MVNO, enter the monthly bill on the rate table as it is in the 24-month formula and compare. [2]
Q3. Where and how do I apply for the selective plan discount?
You apply at a store of the carrier you use, and you need to bring your ID. [2]
Q4. Can I re-enroll in the selective plan discount for a phone whose contract has ended?
Even when you sign a new contract with a used phone whose 24-month contract has expired, you can receive a bill discount equivalent to the public subsidy discount instead. [2]