Good news! From 1st Nov 2025, Greater Belfast customers will benefit from an 8.5% price reduction.
Switch and Get the Cheapest Gas Offer in Greater Belfast*
Credit Meter Offer
or find out How It Works
How It Works
There are 4 easy steps to switch:
-
1
Getting Started
What you will need:
Bank Details: Including sort code and account number. These can be found on your bank statement or cheque book.
SMP Number: This can usually be found at the top right-hand corner of your bill. If you don't have a copy of your bill, simply call our Switch Team on 0330 024 9000 and they can help you. -
2
Switching Your Home
We will contact your current gas supplier on your behalf and keep you updated by letter or email. You have ten working days from the date you submitted your online application to cancel.
-
3
Your Switch Date
Your switch date is usually 5-6 weeks from the date we receive your application online or by phone. You will receive a letter confirming the date that you will become a firmus energy customer.
-
4
Welcome to firmus energy
What happens next?
You will receive your firmus energy welcome pack and notification of your Direct Debit instructions. Finally, sit back and enjoy cheaper natural gas from firmus energy!
- Save 20% when you switch*
- Cheapest* Gas Offer in Greater Belfast
- Flexible bill payment options
- Access your account 24/7
- Hassle-Free Switching
- No Interruption to Your Supply
- Trusted by Thousands
- Friendly, Reliable Service
- Check out our latest Tariff Rates
Pay As You Go Offer
or find out How It Works
How It Works
There are 4 easy steps to switch:
-
1
Getting Started
Your Meter Module Number:
this can be found on your meter.
Your Meter Serial Number: this can also be found on your meter and can start with an ‘E’, 'S' or an 'I'.
e.g. E6 S00123456789. -
2
Switching Your House
We will contact your current gas supplier. We'll send you a letter or email to keep you up to date. You have 10 working days from the date you submitted your application online to cancel.
-
3
Your Switch Date
Your switch date is usually 5-6 weeks from the date we receive your application online or on the phone. You will receive a letter confirming the date that you will become a firmus energy customer.
-
4
Welcome!
What happens next?
We will write to you to confirm you are a firmus energy customer and the steps you need to carry out to update our tariff on your meter. If you have a blue PAYG card we will send you a new firmus energy card.
- Enjoy £200 welcome bonus**
- Best PAYG gas offer**
- Easily manage your costs
- Only pay for what you use
- Hassle-Free Switching
- No Interruption to Your Supply
- Trusted by Thousands
- Friendly, Reliable Service
Offline Belfast Credit Meter
Paying by Direct Debit is optional with the offline tariff however if you do, you will receive a discount of £22.05 per annum.
Connect NowNot connected to natural gas yet?
Phoenix Natural Gas, owns, operates and develops the natural gas network throughout the Greater Belfast area. firmus energy have a licence within this area to supply natural gas. Please contact a member of Phoenix's connection team to discuss your options 03454 55 55 55.
Greater Belfast’s Cheapest Offer* for the Average Domestic Credit Customer: Comparison is based on effective unit rates which include all supplier discounts in Belfast, with effect from 1st November 2025, and calculated using the Ofgem average domestic usage of 12,000kWh. Customers obtain firmus energy’s effective unit with an average consumption of up to 12,500kWh. If your annual usage is above this, it is not the cheapest unit rate. Actual average consumption varies due to weather conditions, changes in energy efficiency and householder behaviour. Contact us and we will be happy to talk you through our rates, the 20% Welcome Discount (Domestic)* or any queries that you may have. Correct as of 16/10/2025. Verify at Cheapest Offer*. New customer offer only, terms and conditions apply 20% Welcome Discount (Domestic)* T&Cs.
Greater Belfast’s Best Offer** for the Average Domestic PAYG Customer: Comparison is based on effective unit rates which include all supplier discounts and welcome credit in Belfast, effective from 1st November 2025, and calculated using the Ofgem average domestic usage of 12,000kWh. Customers obtain firmus energy’s effective unit with an average consumption of up to 12,000kWh. If your annual usage is above this, it is not the best unit rate. Actual average consumption varies due to weather conditions, changes in energy efficiency and householder behaviour. Contact us and we will be happy to talk you through our rates, the Welcome Bonus* or any queries that you may have. Correct as of 16/10/2025. Verify at Best Offer**. New customer offer only, terms and conditions apply £200 Welcome Bonus** T&Cs.
