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Why choose
firmus energy?

Great Savings for customers - enjoy our best value rates

Hassle-free switching - we handle the process for you

No interruption to your supply - just great service & a smooth switch

Trusted by thousands - heating homes across Northern Ireland

Friendly, reliable service - contact us by phone or email, 5 days a week

Greater Belfast’s Cheapest Offer* for Domestic Credit Customers based on the 24% Welcome Bonus Discount. Customers who avail of this introductory offer will receive a 24% discount off the standard Greater Belfast Home Gas Tariff – Credit Meter Online or Offline (subject to customer choice of tariff) as a separate line on their bill. Contact us and we will be happy to talk you through our rates, the 24% Welcome Discount (Domestic)* or any queries that you may have. Correct as of 02/02/2026. Verify at Cheapest Offer*. New customer offer only, terms and conditions apply 24% Welcome Discount (Domestic)* T&Cs.

Save over £100.00† for Domestic Credit Customers: Savings based on an annual consumption of 12,000kWh, or higher, calculated using the firmus energy Greater Belfast Home Gas Tariff – Credit Meter Online with introductory 24% discount and Online Account Discount applied in comparison to the SSE Direct Debit Budget Plan including SSE Airtricity Discount. Customers who have a lower annual usage than 12,000kWh will save less than £100.00. Contact us and we will be happy to talk you through our rates, the 24% Welcome Discount (Domestic)* or any queries that you may have. Correct as of 02/02/2026. Verify at Save Over £100†. New customer offer only, terms and conditions apply 24% 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.