What does data rollover mean for my mobile data allowance?

We use mobile data all the time but sometimes we find ourselves in situations when we get slightly worried about our data consumption. For example, if you get 10 GB of data allowance as part of your monthly mobile plan and by the middle of the month you have already consumed 7 GB, you may find the situation slightly stressful. Data rollover is something that can alleviate some of that stress especially if you are someone who consumes a lot of data. We don’t always have the same data usage behaviour; there are months when we mostly rely on WiFi only, but there are other months when we do lots of outdoor activities and end up using a lot of cellular data for watching YouTube videos, Facebook updates, Zoom calls, etc. Let’s dive into the details to understand what data rollover is and how it works. Also, to help you manage your data consumption better, you may check out our dedicated post on the data cap feature and the spend cap regulation.

Data rollover means that any unused mobile data from your monthly data allowance can be carried forward into the following month. For example, if you get 5 GB per month from your mobile operator and only use 3 GB in a month, a data rollover will add the remaining 2 GB to your next month’s allowance.

What happens to unused mobile data?

Mobile plans or tariffs come in many forms, and all monthly plans are generally built in a way that allows a customer to use their monthly allowance each month. However, if you don’t fully consume all the mobile data included in your monthly allowance, you will lose whatever data you are left with at the end of the month. So, for example, if you have a mobile plan that gives you 25 GB of data each month and you only consume 20 GB in a given month, you will not be able to carry forward the remaining 5 GB to the following month unless your service provider offers a data rollover with your mobile plan.

What does data rollover mean?

When you have a data rollover from your mobile operator, it means that any leftover or unused data from your monthly mobile data allowance can be carried forward into the following month. For example, if your monthly allowance includes unlimited minutes and texts with 20 GB of data, and you consume only 17 GB in a given month, the remaining 3 GB can be carried forward to the next month.

How does the rollover data work?

Data rollover is not a regulation, and mobile operators have a choice whether to offer it or not. Mobile operators that offer the data rollover can also choose the tariffs they want to offer the rollover with. If we look at the UK market, mobile network operators (MNO) usually only offer data rollover on prepaid (pay as you go) tariffs. The MVNOs (Mobile Virtual Network Operators) that piggyback on any of these MNOs can offer data rollover differently (e.g. on pay monthly and/or prepaid) depending on the value they want to give to their customers. The duration within which the rolled-over data must be consumed also differs, and MNOs and MVNOs can choose whichever approach works for them. Generally, the rolled-over data is carried into the following month only once, and if the customer does not consume it, they will lose it.


Let’s use an example to understand the concept of data rollover. Just remember that this is only one example based on how some mobile operators offer data allowance. Your mobile operator may have a completely different approach to how their data rollover works. Imagine you are on a pay-monthly tariff from a mobile operator that gives you 1000 mins, unlimited texts and 25 GB of data as part of your monthly allowance. Let’s now assume that you consume 22 GB of your mobile data in July, which leaves you with 3 GB of unused data. With a data rollover built into your tariff, you can take this 3 GB of unused data into the following month, August, making your total data allowance for August to be 28 GB (25 GB + 3 GB).

Example of a mobile plan or mobile tariff

Does rollover data get used first?

One common question on data rollover is if the rolled-over data is consumed before your regular monthly data allowance or is it used once you have exceeded your regular allowance. Let’s use an example to understand this concept. Let’s assume that your regular monthly allowance includes 25 GB of data and you consume 22 GB of data in July. You can carry forward the unused 3 GB to August. Here, a mobile operator can take at least two different approaches to offer you a data rollover:

  1. Approach # 1 – The operator may have a policy that any rolled over data must be consumed before you can start using your regular monthly allowance. So, in August, you will use the 3 GB first and once you have used it fully, only then will you start cosuming the 25 GB.
  2. Approach # 2 – The operator may have a policy that any rolled over data must only be consumed once you have used up your regular monthly allownace. Using this approach in the same example, in the month of August, you will first use your regular 25 GB which is part of the monthly allowance. When you have consumed the 25 GB fully, only then will you be able to access the 3 GB of rolled over data.

How long does rollover data last?

The duration within which the rolled-over data must be consumed depends on how your mobile operator defines data rollover. One common approach in the UK and other countries is that you can take any unused data forward only once, and that data must be consumed within the following month. If you don’t use it in the following month, then you will lose it. So, for example, if you have some data leftover in the month of July, you can carry it forward to August. But you must consume it in August otherwise you will lose it. This is not the only approach and some service providers also offer longer durations but that isn’t common.

Nowadays, with the 5G networks, many mobile operators are already offering unlimited data, which essentially means you don’t have to keep counting how many GBs of data you are consuming. However, it is important to pay attention to your operator’s small prints and the Fair Use Policy (FUP). Some operators have the policy to apply data throttling on certain tariffs if customers don’t abide by FUP. With throttling, your mobile operator can put a cap on the maximum speed you get on their mobile network after you have used up your monthly allowance e.g. a speed cap of 150 kbps. In other cases, they may restrict you to a lower network technology than you normally use when you exceed your allowance. For example, instead of the 4G LTE network that you mostly use, they may limit you to 3G networks to lower your data speed and therefore data consumption.

Here are some helpful downloads

Thank you for reading this post, I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need some extra support, especially when preparing for a new job, studying a new topic, or maybe just buying a new phone. Whatever you are trying to do, here are some downloads that can help you:

Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy, which explains the network nodes, e.g., BTS, MSC, GGSN etc.

Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience, which is why I’ve carefully put together a few slides to get you started in no time. So if you work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on the product overview and product roadmap.

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