| Tamar Composting (East Anglia) Limited | Water & waste | 2006 |
| Tamar Energy (Hermes Holdings) Limited | Financial services | 2014 |
| Tamar Energy (Holdings) Limited | Financial services | 2014 |
| Tamar Energy Development Company Limited | Administrative & support | 1999 |
| Tamar Energy Limited | Construction | 2011 |
| Tamar Energy Operating Company (One) Limited | Financial services | 2014 |
| Tamar Organic Waste Limited | Water & waste | 2014 |
| Tamar Renewable Power (Basingstoke) Limited | Energy | 2014 |
| Tamar Renewable Power (Essex) Limited | Energy | 2010 |
| Tamar Renewable Power (Hoddesdon) Limited | Energy | 2014 |
| Tammywachter Limited | Health & social care | 2022 |
| Tamsheela Ilyas Ltd | Wholesale & retail | 2025 |
| Tamuka Solutions Limited | Professional & scientific | 2022 |
| TAN & Beauty Hub Ltd | Other services | 2022 |
| Tana Thai Limited | Hospitality | 2017 |
| Tana Thai MK Limited | Hospitality | 2020 |
| Tandemlake Limited | Real estate | 1988 |
| Tandyaz Investments Ltd | Real estate | 2024 |
| Tango Delta Papa Limited | Administrative & support | 2021 |
| Tanna Properties Limited | Real estate | 2024 |
| Tannis - Evans Ltd | Construction | 2026 |
| TAP4LESS Ltd | Wholesale & retail | 2023 |
| Taqwa Homes Ltd | Real estate | 2022 |
| Tara Ventures Limited | Information & communication | 2023 |
| Taras Active Groups Ltd | Health & social care | 2025 |
| Taras Property Management Limited | Real estate | 2013 |
| Target Physiotherapy Limited | Health & social care | 2025 |
| Tartarian Holdings Ltd | Construction | 2019 |
| Tartik Solutions Ltd | Information & communication | 2020 |
| TASK4CARE Ltd | Administrative & support | 2023 |
| Tasnim Investment LLP | | 2014 |
| Tasnim Property Ltd | Real estate | 2019 |
| Taste Italian Bistro Ltd | Hospitality | 2024 |
| Tasty Dosa Ltd | Hospitality | 2025 |
| Tasty Takeaways Limited | Professional & scientific | 2017 |
| Tattershall Management Limited | Extraterritorial | 2017 |
| Tattoo Boutique Ltd | Wholesale & retail | 2024 |
| Tauro Advisory Ltd | Professional & scientific | 2019 |
| Taurus Construction (Northants) Limited | Construction | 2025 |
| Taurus Dental Prosthetics Ltd | Manufacturing | 2019 |
| Taurus Kitchens Ltd | Construction | 2025 |
| Taurus Marketing Hub Ltd | Administrative & support | 2024 |
| Tavener Transport Ltd | Manufacturing | 2023 |
| Tavistock Curry Ltd. | Hospitality | 2019 |
| Tavistock News (PVT) Ltd | Wholesale & retail | 2021 |
| Tax and Accounting Hub Ltd | Professional & scientific | 2013 |
| Tax Matters Direct Limited | Professional & scientific | 2011 |
| Taxily Limited | Transport & logistics | 2022 |
| Tayas Inks Ltd | Manufacturing | 2024 |
| Taylanada Limited | Wholesale & retail | 2021 |
| Taylo Delivery Ltd | Transport & logistics | 2023 |
| Taylor Brightwell Limited | Real estate | 2008 |
| Taylor Cooling Solutions Ltd | Construction | 2025 |
| Taylor Land and New Homes Southern Limited | Real estate | 2013 |
| Taylor Land Limited | Real estate | 2010 |
| Taylor Made New Homes Limited | Real estate | 2010 |
| Taylor Made Properties (Palgrave) Limited | Real estate | 2022 |
| Taylor Made Residential Limited | Real estate | 2017 |
| Tays Support Service Limited | Health & social care | 2020 |
| Tazwell Ltd | Professional & scientific | 2018 |
| Tbase Consultancy Ltd | Construction | 2020 |
| TBC (East) Limited | Construction | 2012 |
| TBC Bedford CIC | Administrative & support | 2024 |
| TBD Solutions Ltd | Construction | 2019 |
| TC Mercatus Ltd | Professional & scientific | 2026 |
| TC Publishing Ltd | Information & communication | 2023 |
| Tcmoncrieff Ltd | Wholesale & retail | 2025 |
| Tconsult Technologies Limited | Information & communication | 2008 |
| TCP Commercial Services Ltd | Transport & logistics | 2018 |
| TCP Services Luton Limited | Administrative & support | 2025 |
| Tcpc Holdings Limited | Financial services | 2023 |
| Tcxpc Building Services Ltd | Real estate | 2023 |
| TDA Garage Ltd | Wholesale & retail | 2022 |
| TDF Heritage Holdings Ltd | Financial services | 2018 |
| Tea and Herbal Solutions Ltd | Professional & scientific | 2018 |
| Teaching Tomorrow Ltd | Administrative & support | 2023 |
| Teachme Limited | Information & communication | 2010 |
| Teal Homes Ltd | Construction | 2015 |
| Team Builders (MK) Ltd | Construction | 2014 |
| Team DO the Thing Ltd | Arts & recreation | 2025 |
| Team Griffiths Limited | Construction | 2012 |
| Team Hurricane Ltd | Professional & scientific | 2014 |
| Team Larbey Racing Ltd | Arts & recreation | 2021 |
| Teamology Limited | Professional & scientific | 2014 |
| Tears&Joy Ltd | Other services | 2025 |
| TEC Fire and Security Limited | Construction | 2011 |
| Tech IT Services Limited | Wholesale & retail | 2024 |
| Techcourse Ltd | Real estate | 2023 |
| Techdrive TD Limited | Administrative & support | 2018 |
| Techgala Ltd | Wholesale & retail | 2025 |
| TECHIE2YOU.COM Ltd | Information & communication | 2011 |
| Techies Limited | Information & communication | 1992 |
| Techlink IT Ltd | Information & communication | 2019 |
| Technical Studio Services Limited | Wholesale & retail | 2014 |
| Technical Tactician Limited | Information & communication | 2026 |
| Technicool Services Limited | Construction | 2015 |
| Technology Booster Limited | Information & communication | 2021 |
| Techprohub Ltd | Other services | 2023 |
| Techventa Group Ltd | Information & communication | 2023 |
| Techvita Ltd | Information & communication | 2020 |