How to Recharge or Extend Your Korea SIM or eSIM

To keep your Korea SIM or eSIM working past its expiry, you add recharge credit to the line you already have, rather than buying a new SIM. The top-up keeps your number, your settings, and (on a real line) your registration intact, and it resets your data and validity for another cycle. On a prepaid (선불) line the credit usually runs for about 30 days per cycle, so you recharge monthly to stay connected. You need no new SIM, no new eSIM QR, and no new ARC. This guide covers who needs to recharge, how credit and validity work, and what happens if a line lapses.

Last updated: June 2026. This is general information, not legal, immigration, or financial advice. Recharge terms and identity-verification rules can change, so confirm your own line’s status with your carrier.

Who needs to recharge, and who just buys again?

You recharge when you already hold a line worth keeping: a prepaid number with apps and contacts tied to it, or a long-stay line you want to carry forward. You buy fresh when the SIM was a one-trip data plan with nothing attached, where letting it expire costs you nothing.

The split comes down to what the SIM carries. A short-trip data eSIM, the kind tourists and new arrivals start on, has no Korean number and no account behind it, so there is rarely a reason to extend it. When the data runs out you just buy the next plan sized to your next trip. A prepaid line with a Korean number is a different story. That number is sitting inside KakaoTalk, your saved contacts, and any service you registered with it, so you recharge to keep it alive rather than starting over. Long-stay residents on a monthly plan are a third case, and they usually do not “recharge” at all, because a postpaid (후불) line bills automatically each month.

The quick version

How does recharge credit work?

Recharge credit is a payment applied straight to your existing line. There is no new SIM and no reinstall, your current number keeps working, and the top-up resets your data allowance and validity for the next cycle. On the recharge products Kimchi handles, you order the tier you want, then send your line details so the credit can be applied to your active number.

The mechanics are the same whether your line runs on KT, SK Telecom, or LG U+: the credit tops up the prepaid balance behind the number you already use. Most prepaid tiers pair a monthly data allowance with a validity window, so a top-up does two jobs at once. It refills the data, and it pushes the expiry date forward. What it does not do is change who the line is registered to, so recharging never re-runs identity verification or asks for your ARC again. That is why a top-up is quick: it is a balance event, not a new sign-up.

The tiers, side by side

Kimchi’s prepaid recharge credits come in three tiers on each network, and the data per cycle scales with the price while the 30-day validity stays the same across all three. Both lines run on KT’s nationwide network, so coverage is identical; you are choosing on data volume, not signal. The figures below are current as of June 2026, taken from the live product pages, and can change, so confirm the tier on the page before you order.

The two networks shape their middle tier differently. LG U+ gives a flat 71GB to spend across the month, while the SKT Eyes Mobile Basic tier front-loads 11GB and then refreshes 2GB each day, which suits steady daily use more than one heavy week. Pick the tier that matches how much data you actually use in a month rather than defaulting to the largest one.

How long does recharge credit last in Korea?

On these prepaid lines, recharge credit is valid for about 30 days from when it is applied, so you top up once a month to keep the line active. If you stop recharging, the line does not vanish overnight. It winds down in stages before it is finally cancelled.

Kimchi’s recharge listings spell out the cycle: “Purchased credits are only valid for 30 days upon receiving date. Users must recharge their credits monthly to maintain the service” (LG U+ recharge credit). The same pages describe what happens when a line goes quiet: “After 90 days, all the services will be stopped, and be able to receive calls and texts for an additional 10 days,” after which an un-recharged SIM “will automatically be canceled.” The practical takeaway is to recharge before your 30-day window closes, not after the line has already stopped, because a cancelled prepaid number can be reassigned and is not always recoverable.

Those timings come from the current recharge product terms and can vary by carrier and plan, so check your own line’s status with the carrier if you are close to a deadline.

Do I lose my Korean number if I let the SIM expire?

If you recharge within the grace period, you generally keep your number. If the line is cancelled outright, the number can be released and reassigned, and at that point it is usually gone. So the answer depends entirely on whether you top up in time.

This is the costliest slip to avoid, because a Korean number is woven into more than calls. It sits in KakaoTalk, in saved contacts, and in any account where you used it to register, so losing it can mean re-verifying services and chasing down every place the old number lived. The fix is cheap: set a monthly reminder a few days before your recharge window closes, and top up on schedule. If you travel home for a stretch and want to hold the number without using it, a small recharge each cycle still costs far less than recovering a cancelled line, if recovery is even possible.

Can a tourist or short-term visitor recharge a line?

A tourist can extend a data eSIM by buying more data, but tourists do not hold a recharge-style Korean number in the first place, so there is no number-carrying line to keep alive. On arrival, foreigners get data, not a Korean phone number, and a real 010 number needs a physical Alien Registration Card plus a long-stay residence visa; the registration-fact certificate (외국인등록사실확인서) does not work for activation, and the card itself usually takes about two to three weeks to arrive. Eligibility and the document rules sit with the Korea Immigration Service via the HiKorea portal. That is why recharge matters mainly for residents.

If your stay is short, the cleaner path is to size your next data plan to your next trip rather than nursing an expiring one. The Korea data eSIM plans come in 15-day and 30-day options, so you pick the window you need and activate it when you land. If you are a long-stay resident who already converted to a real number, recharge is your tool for keeping that line healthy month to month. For who qualifies for a Korean number and the order it happens in, see our guide on how to get a Korean phone number as a foreigner.

How do I actually recharge through Kimchi?

You buy the recharge tier that matches your network and data needs, then send your line details so the credit lands on your existing number. There is no new SIM, no new QR, and no reinstall. A few things are worth getting right before you order. First, confirm your network and pick the right tier: check whether your line is SKT Eyes Mobile or LG U+, then size the tier to your monthly data use, since the tiers differ mainly in the data allowance and not the 30-day validity. Second, order while the line is still active, which avoids a gap and keeps the number well clear of the cancellation timeline. Third, have your line details ready to send the moment you order, because the credit is applied to that active line and the new cycle starts from there. One thing to double-check before you pay: a completed recharge cannot be cancelled, so confirm both the tier and the line first.

Verify it yourself (official sources)

Recharge terms, validity windows, and identity-verification rules are set by the carriers and the regulator, and they change, so check the primary sources before making decisions that depend on them. Korea’s mobile subscription and identity-verification policy sits with the Ministry of Science and ICT (MSIT, 과학기술정보통신부). For anything tied to your visa, ARC, or long-stay status, the Korea Immigration Service and the HiKorea portal are the authority, and the Foreigner Information Center can be reached on 1345 inside Korea. The exact validity, grace, and cancellation timings quoted above come from Kimchi’s current recharge product terms and can differ by carrier and plan, so confirm your own line with the carrier.

Frequently asked questions

Can I switch to a bigger tier or a different network when I recharge?

You can change tiers between cycles: recharge at Budget one month and Premium the next, sizing each top-up to that month’s data needs. Switching networks is different, because the recharge credit applies to the line you already hold, so an SKT Eyes Mobile line takes SKT Eyes Mobile credit and an LG U+ line takes LG U+ credit. Moving between carriers is a port, not a recharge. If you are unsure which line you have, check the SIM packaging or ask before you order so the credit matches.

What line details do I need to send to apply the credit?

After you order, Kimchi applies the credit to your existing line once you send the details that identify it, typically your Korean phone number and which network the line runs on. Because the credit cannot be undone once applied, the safe step is to confirm the number and the network are correct before the top-up is processed. Sending the wrong line’s details means the credit lands on the wrong number, so it is worth a second look.

I already missed a few recharges. Can I still bring my line back?

Possibly, if you act inside the lapse window. The product terms describe service stopping after about 90 days, with roughly 10 more days when the line can still receive calls and texts before automatic cancellation. A new top-up during that window generally revives the line, but once the SIM is cancelled the number can be reassigned and is often gone for good. If you are unsure where your line stands, confirm with the carrier before assuming it is recoverable, because the exact timing varies by plan.

I’m leaving Korea for a few months. How do I keep my number without wasting data?

Keep recharging on the smallest tier each cycle so the line stays inside its 30-day validity, even if you barely touch the data. The point is to keep the line active rather than to use it, and a small monthly top-up costs far less than recovering a cancelled number, assuming recovery is even possible. Set a reminder a few days before each window closes so a recharge does not slip while you are away.

Does recharging re-run identity verification or need my ARC again?

No. A top-up is a balance event on a line that is already registered to you, so it does not re-run identity verification (본인확인) or ask for your ARC again. The line’s registration stays as it was when the number was first issued. You only deal with ARC and verification when a line is first set up, not when you recharge it.

What’s the difference between recharging and converting a bridge SIM?

Recharging tops up an existing prepaid line to extend its data and validity. Converting is the one-time switch a bridge SIM makes from its 60-day data window to a 12-month postpaid plan, which is when your real Korean number is issued. If you hold a Welcome SIM or Korea Starter SIM still inside its 60-day window, you convert before day 60 rather than recharging.

Can I recharge a line that is in someone else’s name?

The credit attaches to the line rather than to whoever pays for it, so a recharge can be applied to a line registered to another person as long as you have that line’s correct details. What a recharge cannot do is change whose name the line is registered under, since that registration was set when the number was first issued and is untouched by a top-up. For a line you do not control, confirm with the account holder before ordering so the credit goes to the right number.

Keeping your line alive the easy way

Recharge is the quiet half of staying connected in Korea: less dramatic than getting your first number, but the thing that keeps that number yours. Top up before your cycle closes and the line carries on with everything attached to it; let it lapse and you risk handing the number back. A monthly reminder is usually all it takes.

If you already have a prepaid line to keep alive, add the recharge credit that matches your network: SKT Eyes Mobile recharge credit or LG U+ recharge credit. If you are still figuring out which line you need, or you are a visitor sizing a data plan for a trip, start from the Korea SIM and eSIM shop and pick the option that fits your stay.