How to Top Up a Prepayment Meter and Use Emergency Credit

A prepayment meter is paid for before the energy is used, not after: credit is loaded onto a key, a card or, on a smart meter, straight onto the meter itself, and the supply runs only while that credit lasts¹. Traditional meters are topped up in person at a shop carrying PayPoint or Payzone, or at a Post Office, using the meter's key, card or a barcode². A smart meter in prepayment mode needs no key or card at all: credit is bought online, through the supplier's app, by text message or over the phone, and sent to the meter remotely³.

Where a top-up cannot reach the meter over the air, it is entered by hand as a 20-digit code, also called a unique transaction reference number, printed on the receipt or payment confirmation⁴. In Northern Ireland, Keypad meters work this way as standard: a code bought online or in a shop is typed into the meter's keypad. Power NI customers can buy that code online as a guest with a 19-digit Keypad Premise Number, which usually begins 9826908501, and the property postcode, with no registration and no Keypad card needed⁵.

When credit runs out, most meters offer a small emergency credit allowance, commonly around ten pounds, which behaves like an overdraft and is repaid from the next top-up⁶. Beyond that, the position is blunt: once credit is exhausted and emergency credit is used up, no energy can be drawn until the meter is topped up again⁷.

Pay first, then use: what that means day to day

With a prepayment meter you pay for gas or electricity in advance of using it, on a pay-as-you-go basis¹. Older meters read a smart card, a key or a token, and a few still take coins². Credit bought in a shop is written onto the key or card at the till, then carried home and inserted into the meter, which transfers the money across and starts counting it down.

One practical consequence is that the supplier does not need a meter reading to bill: the meter has already been paid, so consumption is settled as it happens rather than after a bill arrives⁹. That removes estimated billing, but it also removes the cushion a credit account gives. There is no month's grace, and no direct debit smoothing winter against summer. The household's supply depends on someone being able to get to a top-up point, or get online, before the balance reaches zero.

The second consequence is that prepayment is often used as a debt mechanism. Suppliers frequently recommend a prepayment meter to customers already in fuel debt precisely because it stops further debt building and lets the supplier collect part of the arrears from every top-up¹⁰. That is the trade: tighter control over spending, at the cost of paying for past debt out of every payment and of losing supply if a payment cannot be made.

Ways to top up: shop, key, card, app or code

The route depends on whether the meter is a traditional prepayment meter or a smart meter running in prepayment mode.

The smart route is the significant change for households. Because credit is sent over the smart network rather than carried on a plastic key, a prepay customer with a smart meter should be able to top up online, and suppliers offer telephone, text and app top-ups as alternatives¹⁴. Ofgem's expectation is that a smart meter customer should be able to top up in the way that suits them, in person or remotely¹⁵. A smart meter top-up should appear on the meter within one hour⁸.

Not every household wants to give up cash. Where someone prefers to pay in a shop, a supplier can issue a barcode, card or reference number to hand over at the counter, and the credit is then applied to the smart meter¹³. Where a shop is inconvenient or unsafe to reach, a supplier may agree to an alternative such as top-up by text message, a smart meter in prepayment mode that can be topped up online, or a move to a credit meter billed monthly or quarterly¹³. Those are arrangements to ask about rather than automatic rights.

Topping up a Northern Ireland Keypad meter

In Northern Ireland, prepayment is the Keypad system, and the identifying test is simple: a meter paid for by top-up is a keypad meter, while a meter that produces a monthly or quarterly bill is a credit meter¹⁶. Keypad meters are installed as standard single-rate units and as multi-rate units with Economy 7 for homes with storage heating¹⁷. Each electricity supplier publishes its own top-up arrangements, and Northern Ireland Electricity Networks, which owns the meters, points customers to those supplier pages rather than handling top-ups itself¹⁸.

For a Power NI Keypad, online top-up requires the 19-digit Keypad Premise Number, which usually begins 9826908501, together with the postcode. No registration is required for a guest top-up, and the Keypad card is not needed to buy credit online⁵. Customers who do register an online account can save payment details for faster future top-ups, view previous top-up codes and letters, manage the account and use the Power NI Perks rewards scheme⁵.

Keypad meters also have a physical limit on the supply they draw. Where a property repeatedly overloads its connection, the route is an application to alter the existing network equipment to increase the connection capacity, which is a network matter rather than a supplier one¹⁶.

Entering a top-up code by hand

Where credit cannot be delivered over the air, it is added manually using the 20-digit code shown on the receipt or payment confirmation, known as the unique transaction reference number⁴. The code is unique to one meter and one payment, which is why it cannot be reused and cannot be applied to a different property's meter.

The sequence on a keypad meter is straightforward in principle:

1. Buy the credit and obtain the code, on a printed receipt, by email, by text or through the supplier's app⁴.
2. Wake the meter's keypad and begin code entry, using the meter's entry key.
3. Type the digits in order, checking the display as each group appears.
4. Confirm the entry and wait for the meter to accept the code and show the new balance.
5. Keep the receipt or code record until the balance has visibly increased.

Meters differ in which key starts and confirms entry, and in how long they wait before clearing a part-typed code, so the meter's own instruction label or the supplier's guidance for that model governs the exact keystrokes.

Codes are most often rejected for mistyping, for belonging to a different meter, or for having already been applied. Government support vouchers behave differently again: prepayment customers may be required to redeem such vouchers at a local top-up point rather than keying them into the meter¹⁹. Vouchers for traditional prepayment meters have been issued by text, email or post, or credited automatically at the next top-up²⁰. Where a code will not take, the supplier that issued it is the only party that can verify or reissue it.

Emergency credit: a limited overdraft, not free energy

Most prepayment meters carry an emergency credit budget that can be drawn on when the ordinary balance runs out, and it is limited⁶. It is designed to maintain supply for a short period after regular credit is exhausted, and it is reclaimed from the next top-up⁸. Suppliers commonly provide around £10²¹. Age UK's position is that "your supplier should offer you emergency credit wherever possible"²².

Activation differs by meter. On a traditional meter it is usually triggered by inserting the key or card, or by pressing a button on the meter. On a smart meter in prepayment mode, emergency credit is generally activated at the meter itself or through the in-home display²³, and Smart Energy GB describes a dedicated emergency credit button giving "a bit of extra time before you are able to top up"²⁴. An in-home display in prepay mode shows the available balance for each fuel and how close the household is to its next top-up¹², and consumer testing describes displays that show the credit balance, alert the user when the balance is running low and let emergency credit be activated²⁵.

Repayment is the part households most often underestimate. The amount used is repaid when the meter is next topped up²⁶, either in full or, by arrangement with the supplier, a little at a time²⁷. Emergency and friendly credit usually have to be repaid in full before they can be used again²⁸. A top-up made after a spell on emergency credit therefore buys less energy than the same top-up made from a positive balance.

Where a household cannot afford to top up at all, a separate route exists. Suppliers can apply temporary credit, often called additional support credit, to a prepayment meter or a smart meter in prepayment mode²⁹. It is not always added automatically, so the supplier has to be contacted³¹. It too is recovered from future top-ups³².

Friendly credit: staying on overnight and over holidays

Friendly hours credit is a separate protection from emergency credit. It applies where a meter is running low at times when top-up points are closed: overnight, at weekends and on public holidays³³. Citizens Advice describes the same protection as temporary credit available if credit runs out at night, at weekends or on bank holidays³⁴. Whether it is applied automatically or has to be requested depends on the supplier³⁵.

The practical effect is that a meter reaching zero at ten on a Sunday evening should not necessarily cut the heating off until Monday. The practical limit is that friendly credit, like emergency credit, is repaid from the next top-up and usually has to be cleared in full before it can be drawn on again²⁸. It buys time, not energy.

Suppliers have at times gone further during winter, with measures including payment holidays, restructured payment plans, credit advances to prepayment customers and reducing or waiving standing charges over winter for certain customers³⁶. These are supplier-by-supplier decisions rather than a uniform entitlement, so the only reliable way to know what applies is to ask the supplier directly. Anyone who needs a constant electricity supply for lifesaving equipment, or who cannot safely reach the meter to read or top it up, should make sure the supplier knows, because that changes what the supplier must offer³⁷.

Reading the display: balance, debt and daily cost

Prepayment meters carry a button that cycles through screens, including how much credit remains and the unit rate and standing charge being applied³⁸. On a keypad-style pay-as-you-go meter, pressing 2 shows the cost of usage for the previous day, week and month, which is the quickest way to see whether consumption is rising³⁹. On a smart meter in prepay mode, the in-home display carries the same information in a more readable form, showing the balance for each fuel and how close the household is to needing a top-up¹².

Those screens matter because the balance shown is not always the amount available to spend. Where debt repayment or recovered emergency credit is being taken, part of the balance is already committed. The screens showing standing charge, unit rate and debt recovery are what explain the gap between a £10 top-up and the energy it actually buys. Reading them regularly is also the basis of any attempt to reduce consumption, since the meter is the only record of what the household is actually using. Further detail on meter displays is covered in the guides to taking a meter reading and getting a reading from a smart meter.

Why your top-up buys less than you expect

Three deductions sit between money paid and energy delivered.

• Standing charge. A daily standing charge accrues whether or not energy is used. If a meter is not topped up, for example a gas meter left over summer, that charge builds as a debt, and later top-ups are used to pay off previous weeks' unpaid standing charges³.
• Debt repayment. Repayment may be set as a fixed weekly amount or as a percentage. Where repayment is £6 a week and £10 a week is topped up, £6 goes to the debt and £4 is added as credit. Where repayment is set at 30%, every £10 top-up puts £3 to the debt and £7 to credit. Missed payments are added up and deducted from the next top-up³.
• Recovered emergency or friendly credit. Anything advanced comes off the next payment²⁶.

Debt itself can arrive by several routes: using some or all of the emergency credit, missing a standing charge payment, or being on a repayment plan⁶. Debt from a credit meter account may also be transferred onto a prepayment meter by the energy company, with repayments then taken automatically at every top-up³. That transfer is the mechanism behind many unexpectedly small credit balances.

The cost position is not neutral. Prepayment meters have been described as more expensive to run, harder to switch away from, and capable of leaving a household without electricity if the meter is not kept sufficiently topped up⁴⁰. Households carrying arrears can read more on energy debt write-off grants and on switching supplier with a prepayment meter and debt.

Lost key, lost card, or a supplier that fails

If the key or card is lost, the supplier should send a replacement, and in the meantime should be able to authorise a temporary card at the nearest PayPoint, Payzone or Post Office so the household is not left without a way to pay⁶. Power NI sends a replacement Keypad card by post and asks for up to three weeks, while online top-up continues in the meantime⁵.

If the supplier goes out of business, the meter can still be topped up as usual, and the new supplier appointed to the account provides information on how to obtain new key cards and tokens⁴¹. Until that new account is properly set up, the advice is to top up only in small amounts, paying only what is needed to get through a few days⁴². Loading a large sum during the transfer risks credit being difficult to trace.

Where the meter itself is at fault, the supplier should confirm the problem and offer a solution, either fixing it remotely or replacing it³. That is covered further in the guide to reporting a faulty or inaccurate meter.

Where prepayment is unsuitable

Prepayment is presented by Ofgem as helpful for households on a tight budget, those who want more control over spending, and those managing debt⁴³. The same guidance is clear that a supplier must offer help where a customer cannot afford to top up, for example by giving extra credit in a vulnerable situation⁴³. A prepayment meter may only be installed without permission where other ways of recovering the debt have not worked⁴⁴.

Circumstances in which prepayment may not be safe and practical include the following.

• The meter cannot be physically accessed to top it up, or the householder is disabled or has a health condition²¹.
• The household cannot afford to top up and includes children aged between two and five¹³.
• Someone in the household needs a continuous supply for health reasons, there is a resident over 75 without support, there are children under two, or no one is able to top up because of incapacity²⁷.
• The nearest top-up point is more than two miles away and the household has no car, which Ofgem has said may make a prepayment meter not reasonably practicable⁴⁵.
• The householder is aged 75 or over, or simply cannot afford to top up²¹.

For energy independence, the honest summary is that prepayment gives a household precise visibility of what it spends and stops debt accumulating unseen, but it deepens dependence in other directions. Supply is contingent on a successful payment, on a shop being open or a network being available, on the supplier's app or phone line working, and, for smart top-ups, on the national smart metering network carrying credit to the meter¹². A household that wants to reduce that exposure has limited levers: keeping a buffer of credit on the meter, knowing the emergency and friendly credit rules before they are needed, and reducing consumption so that each top-up lasts longer. Wider options are set out in the guides to taking more control of your home's energy and to changing from a prepayment meter across the how-to library.