Rollover explained: what carries at renewal and what doesn't

2026-10-11 · Bazyl

At renewal, a residential subscription carries what you didn't use into the next cycle, up to one month's plan. That one rule predicts your balance for any month you care to name, and the rest of this post is the arithmetic. The thing most people get wrong is the cap. Rollover is not "nothing is ever lost": it carries one plan's worth and reclaims the rest.

Here is the rule exactly as billing applies it, then three months worked through on a 50 GB plan, then the case where a plan is the wrong product.

The carry is the smaller of two numbers

At renewal the carry is min(leftover, one month's plan). Anything above one plan is reclaimed. The new cycle starts with plan + carry and expires at the next period end.

On a 50 GB plan with 30 GB left, the carry is 30 and the new cycle opens at 80 GB. With 70 GB left, the carry is 50, the 20 GB above the plan is reclaimed, and the new cycle opens at 100 GB. Same plan, same rule, two different answers, because the second one hit the cap.

One consequence falls straight out of the formula: a cycle never opens above twice the plan. Plan plus a carry of at most one plan is at most two plans. If your dashboard shows 100 GB on a 50 GB plan, you are at the ceiling, and the next renewal reclaims whatever is still above 50 when it runs.

Three months on a 50 GB plan, worked

Numbers in GB. The plan is 50 throughout, and the carry is applied at every renewal:

Month 1   open  50   use 20   left  30
Renewal   carry min(30, 50)  = 30   reclaimed  0
Month 2   open  80   use 10   left  70
Renewal   carry min(70, 50)  = 50   reclaimed 20
Month 3   open 100   use  0   left 100
Renewal   carry min(100, 50) = 50   reclaimed 50
Month 4   open 100

Read the last two renewals. A plan you stop using fills to twice its size and then sheds a full plan every month, and reclaimed gigabytes don't come back. A plan sized to your average month never meets the cap. A plan sized to twice your average meets it from the third renewal on and reclaims your whole surplus every month after that.

Rollover forgives one quiet month. Use 50 GB a month, skip one, and the skipped month's 50 GB sit in your balance for as long as you keep drawing the plan down: every renewal sees 50 left, carries 50, and reclaims nothing. A second quiet month before you've used that surplus is the one that costs you, because then 100 GB are left and only 50 can carry.

Cancel, and the remainder runs to the end of the paid period

Cancelling stops renewals; it doesn't shorten the period you paid for. The remainder stays usable until the end of that period and then expires. Nothing carries, because nothing renews.

Say you have 70 GB left and 12 days to go, and you cancel today. You have 12 days to use 70 GB. On day 13 the balance is zero whether you used 10 of them or all 70. So don't cancel to "lock in" a big balance; cancelling puts a date on it. If you want the data without the renewal, pay as you go is the product for that, and it's the next section.

What this post doesn't cover is what a change of plan size does to a balance mid-cycle. Ask before you change, not after.

A plan costs less per gigabyte than pay as you go, at the same size

Pay as you go starts at 1 GB and never expires. A subscription renews monthly, rolls over, and costs less per gigabyte than pay as you go at the same size. In the 50 GB band, in US dollars, as of 25 September 2026:

• Subscription: $1.34 per GB, so a 50 GB plan is $67.00 a month.
• Pay as you go: $1.68 per GB, so 50 GB bought outright is $84.00.

In euros the same band is €1.12 against €1.40 as of 1 October 2026: €56 a month against €70.

Plans come in 10, 25, 50, 100, 250, 500, 1,000 and 2,000 GB, the per-gigabyte rate falls as the plan grows, down to $0.90 from 1,000 GB up, and the live ladder for your currency is on the pricing page. Rollover is residential only. An ISP subscription renews the same IPs; there are no gigabytes in it to carry.

The $17 a month between the two lines is the price of flexibility, and over a year of steady 50 GB months it adds up to $204. That is the case for the plan. The next section is the case against it.

When pay as you go beats a plan

Pay as you go wins when your use is irregular or one-off, because it never expires and a plan reclaims. Take one 50 GB drop a quarter:

Plan, 50 GB at $67 a month, the drop in month 1
Month 1   open  50   use 50   left   0
Month 2   open  50   use  0   left  50
Month 3   open 100   use  0   left 100
Renewal   carry 50, reclaimed 50
Paid for the quarter: 3 × $67 = $201, used 50 GB

Pay as you go, 50 GB at $1.68
Paid once: $84, used 50 GB, nothing expires, nothing reclaimed

$201 against $84 for the same 50 GB. The plan does hold 100 GB going into month 4, but once the balance sits at that ceiling every quiet renewal reclaims 50 GB, so from then on each quarter costs $201 for 50 GB used. Pay as you go costs $84 a quarter for the same thing and has no renewal to miss.

The size you buy matters too. Pay as you go has its own volume ladder: 100 GB outright is $1.20 per GB, $120, and none of it expires.

If you can pay that once and spread it over four months, you're under the 50 GB plan's $1.34 with no renewal in sight. The plan is for people who'd rather pay $67 a month than $120 up front, and whose months look alike.

So, three cases:

• Your months look alike and you use most of the plan: subscribe, and size the plan to the average month, not the best one.
• One quiet month now and then: subscribe anyway. Rollover keeps that month's data for you until you draw it down.
• Drops a few times a year, or no idea what next month looks like: pay as you go, at the biggest size you can afford, because it never expires.

Check the plan sizes against your last three months of usage on the pricing page; the number to match is your average month, not your best one.