T-Mobile is doing it again: Another free line promo starts tomorrow (3/17)


Stop the madness: T-Mobile is going to be offering another free line promotion starting 3/17/21 whereby existing customers on qualified rate plans who have at least 2 paid voice lines will be able to add a free line once again (via monthly bill credits). Last year, T-Mobile ran four free line promotions that enabled existing customers to add free lines (I took advantage of three of them and wrote about two of them — one here and another one here). Once again, if you’re on T-Mobile it is worth checking this deal out whether you need a line right now or not — and keep in mind that there are a number of discounted device deals you can get when you add a line and a free line counts for device promotions that require adding a line. Unfortunately, deeply discounted plans like the Military Plan, 55+ plan, First Responder plan and the sort are ineligible. Also note that some plans require a few dollars in taxes for the “free” lines (both my old plan and my new plan are tax-inclusive on my 3 paid lines, so the additional lines have been totally free).

The Pixel 4a 5G, which I am currently using as my primary phone, is available for $175 after bill credits when adding a line at the time of writing. I believe that adding a free line will work for that promotion as I was able to get one for 50% off last year when adding a free line (and another for 100% off with a trade-in and new free line).

Reasons why I love this

As noted above, I added three free lines to my account during 2020 (I missed one of the free line deals). When I add this latest free line promotion, I’ll be at 3 paid lines and 4 free lines on my account. There are several things I find awesome about these free line promos:

  • The free lines get the same plan as your paid lines. In my case, my 3 paid lines are now on Magenta Max. That’s the the top-end T-Mobile plan that includes totally unlimited 5G with no throttling and 40GB of mobile hotspot per month per line. That means all 4 of my free lines will have the same completely unlimited 5G data with 40GB of hotspot each. Taxes depend on your plan: since my new Magenta Max plan and my old T-Mobile One plan included taxes in the price for the paid lines, my free lines are totally free. Some plans break out taxes separately for each line – if you’re in that situation, you’ll owe a few bucks in tax each month on your “free” lines.
  • Every line gets access to T-Mobile Tuesdays. Even if you don’t actually need the extra line right now, you can essentially get access to an extra account for when they run the randomly good T-Mobile Tuesdays deal a few times a year.
  • A free line counts for device promotions that require adding a line. Last year, on one of my free lines I added a device for 50% off via bill credits thanks to the free line and on another I added a device that is free after bill credits for adding a (free) line and trading in an older device that I bought cheaply on Swappa.com. Currently, T-Mobile has a number of phones that are free with add-a-line and some that are 50% off (or others with unique promos like the Samsung Galaxy A71 that’s $99 with a new line).
  • It makes a nice gift. You could offer that free line to a friend or family member. Who doesn’t like free cell phone service?
  • Earn 4% APY with T-Mobile Money. This is basically a virtual checking account offered to T-Mobile customers. T-Mobile customers get 4% APY on the first $3K in the account and 1% on the rest (up until this month, the 4% required depositing $200 per month, but starting next month you’ll need 10 debit card transactions per month). While the cap on 4% is low, even the 1% on the remainder isn’t bad at all in the current environment (and 4% on $3K is worth $120 a year). That’s an added bonus that goes with the free cell service gift.

If you’re on T-Mobile and eligible for the free line, it just seems like an easy win. The only “catch” is that you need to keep your lines as-is for 12 months from adding the free line. If you try to cancel a (paid) line, you’ll lose the monthly bill credits that make the “free” line free.

Free/discounted phone deals stack, rebates like Costco don’t

I stacked this successfully once last year, but it looks like that won’t work this time around.

This reddit thread is the authority for info on this deal. I’ve also found the Slickdeals thread useful on the last few deals, with user Jman100 consistently providing excellent information (here is the current deal’s Slickdeals thread). While I was able to successfully stack one free line deal with a $200 Costco rebate for adding that (free) line in-store last year, terms on the previous deal and (and now this one according to reddit and Slickdeals) indicate that you will not qualify for a Costco or other rebate for the free line.

However, as noted above, last year I was also able to stack with deals that offered 50% off a new phone when adding a line and 100% off for adding a line and trading in a device (in one case I bought a cheap older model off of Swappa.com to trade — your local Facebook marketplace might be an even cheaper option). I don’t know for sure which deals will be active tomorrow, but I’m possibly eyeing a Samsung A71 5G for a family member for $99 with a newly added free line. Note that the phone deals are typically via 24 monthly bill credits, so that won’t be exciting for those who don’t want to be tied to T-Mobile for a couple of years.

Note that T-Mobile does have a maximum number of lines per plan. I believe that is 8 lines for most people (though I’ve heard some reports of people who have 9-12 on a plan and business customers are also eligible for this free line promo).

Also note that I think this will stack with T-Mobile’s offers to pay off your existing device when you switch, which (I think?) could be a great deal if you’re just adding one person from another service.

How to determine if you’re eligible

Reddit has great instructions for how to find your plan’s SOC code here (I can never remember the process and always go back to that post) and a screen shot of the eligible SOC codes for this add-a-line deal here.

I switched last month from an old T-Mobile One plan to the new Magenta Max plan and both my old SOC code and new SOC code are on the list, so I’d have been eligible for this new free line either way. As noted in the first paragraph, those with a Military Plan or the 55+ plan or First Responder plan will not be eligible.

Those who are new to T-Mobile

If you’re newly switching to T-Mobile, I think you’ll just get the 3rd line free (which is a standardish promotion from T-Mobile). They are also currently offering to pay off your device and early termination fee up to $650 per line — see this page for more details.

A reader made me aware that T-Mobile has a referral program and I confirmed with T-Mobile support on Twitter that joining through the referral program still qualifies for the device payoff and third line free above. Here’s my referral link. To be clear, this specific free line promotion may not be worth switching for on its own, but if you have been contemplating the switch, the continuance of free line promotions like this one certainly might pique your interest.

Bottom line

If you’re on T-Mobile post-paid with at least 2 paid voice lines and you have an eligible plan, it is worth taking advantage of the free line promotion. The past couple of times, I’ve been able to add the line via T-Mobile on Twitter or via chat in the app, though I think you can also do it yourself online (or do it in-store if you like). Note that people who currently have T-Mobile Home Internet or something like a hotspot but no voice lines might get targeted for 20% off via Insider Hookup starting tomorrow. While those customers without any existing T-Mobile voice lines will just get a third line free (which is a standard promotion from T-Mobile), getting that long-term 20% discount plus a foot in the door for future free line promotions certainly might be worthwhile.

Funny enough, last year I determined that cell phone insurance probably wasn’t a good deal for me and I should just self-insure and earn 5x on my bill via the Chase Ink Cash — but now that I’ve suddenly got 7 devices on my plan, cell phone insurance is looking a lot wiser. Amex Platinum coverage came around just in time for me to stack with 5x on the Business Platinum, so I’ll be glad to have that for the time being (especially considering my great experience with Amex purchase protection on a smashed phone).

H/T: Doctor of Credit, reddit, and Slickdeals

0 0 votes
Post Rating

Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments
Steve A

Thanks for the heads-up on this promo. I just added my 3rd free line to my other 6 phone lines on my account. The T-mobile agent said that she had to change my account since I was maxed out at 8 phone lines, so now I can have up to 12 phone lines – she said technically the max is 15 lines, but my type of account can only go up to 12. I tried to get the A71 for $99, but they were out-of-stock so I ended up with the “free” A11 for a $30 activation fee.


Can the free line be for an iPad data plan? Or only a phone?

Mike Saint

Thanks Nick! I’ve never heard of this. I called TMobile today and sure enough they added a free line for me. $120/month value. And they said the line is free for life as long as I pay my regular bill. Just added a line for my mother in law. Thanks.

Mike Saint

Thanks for that follow-up post. I didn’t know you could get a free phone. I’ll try. Super helpful. I met you up in Seattle a few years ago when you were a speaker at one of the Frequent Travel events. Great to see you so active. Great stuff!


The last time I checked on this I didn’t qualify because I”m on 55 plan. However I believe they said I could add a line to that plan for $20.


Maybe it’s just time to switch from Verizon

Eddie K

I noticed my lines are not completely free. I have to pay additional taxes for those free lines, so I still end up paying about $5/mo per line.


hi, how exactly do you add the free line? i see the option online, but will I still need to check the SOC code to make sure the line is actually free? thank you