| ISKO UK LTD | Christchurch | A rating |
| Isla Sell Physiotherapy Ltd | Looe | A rating |
| ISLA TRADING LIMITED | Edinburgh | A rating |
| ISLACARE LTD | Greater London | A rating |
| Islam & Co Ltd | Liverpool | A rating |
| Islam Catering Ltd | York | A rating |
| ISLAM DEWSBURY | DEWSBURY | A rating |
| Islam Foods Ltd | Hull | A rating |
| Islam's Crawey 1 Ltd T/A Roosters Zone | Crawley | A rating |
| Islamic Academy of Scotland | Glasgow | A rating |
| Islamic Aid | London | A rating |
| Islamic Appeal | Essex | A rating |
| Islamic Bakers and Confectioners | Batley | A rating |
| Islamic Brotherhood | Coventry, | A rating |
| Islamic Centre Central London | London | A rating |
| Islamic Centre Leicester | Leicester | A rating |
| Islamic Community & Education Centre | Stourbrudge | A rating |
| Islamic Cultural Society Luton Mosque | Luton | A rating |
| Islamic Education Centre | Blackburn | A rating |
| islamic educationcultural centre & quran academy | birmingham | A rating |
| Islamic Help | Birmingham | A rating |
| ISLAMIC INTERNATIONAL STORE | PETERBOROUGH | A rating |
| ISLAMIC RELIEF WORLDWIDE | BIRMINGHAM | A rating |
| ISLAMIC SHAKHSIYAH FOUNDATION | London | A rating |
| islamic social and educational trust | Manchester | A rating |
| ISLAMIC SOCIETY OF GLOUCESTER | Gloucester | A rating |
| Islamic welfare foundation London | LONDON | A rating |
| Islamicfinanceguru Limited | London | A rating |
| Islamiyah Girls' High School | Blackburn | A rating |
| ISLAND AUDIT AND CONSULTING SERVICES LIMITED | London | A rating |
| Island Care Limited | Cowes | A rating |
| Island City Practice | Portsmouth | A rating |
| Island Dairies Farm Limited | Dromore | A rating |
| Island Dental Care Limited | Kent | A rating |
| Island Healthcare Ltd | Ryde | A rating |
| Island Pacific (UK) Ltd | Saffron Walden | A rating |
| ISLAND SEA SUPERMARKET LTD | Birmingham | A rating |
| Island Technology (UK) Limited | Reading | A rating |
| Island View Ltd T/A City Lets | LEICESTER | A rating |
| Islandbridge Capital Limited | London | A rating |
| Islandbridge Properties Limited | Loughton | A rating |
| Islanders Fish Restaurants and Take Away Ltd | Canvey Island | A rating |
| Islands Chocolate | London | A rating |
| ISLANDUK LTD TA Spice Island | London | A rating |
| ISLATT LTD | london | A rating |
| Islay and Jura Dental Practice | Bowmore | A rating |
| Islay Crab Exports Ltd | Port Ellen | A rating |
| ISLAY FRIGATE HOTEL LIMITED | Tarbert | A rating |
| Islay House Ltd | London | A rating |
| Isle Care (Axholme) Ltd | Doncaster | A rating |
| Isle of Flowers (Stations) Ltd | LONDON Paddington | A rating |
| Isle of Raasay Distillery | By Kyle | A rating |
| Isle of Skye Candle Company Ltd | Portree | A rating |
| Isle of Wight College | Newport | A rating |
| Isle of Wight NHS Trust | Newport | A rating |
| Isle of Wight Visionplus Limited t/a Specsavers | Newport | A rating |
| Isle Utilities Ltd | London | A rating |
| Islestarr Holdings Limited | London | A rating |
| Isleworth & Syon School For Boys | Isleworth | A rating |
| Isleworth Greengrocer Ltd | Isleworth | A rating |
| Islington Community Sports Academy | London | A rating |
| Islington GP Group Limited | London | A rating |
| Islington House Medical Centre | Liverpool | A rating |
| ISLINGTON SMILE GROUP LIMITED T/A YOURDENTAL WELLNESS | Islington | A rating |
| Islington Visionplus Limited t/a Specsavers Islington | London | A rating |
| Islip Manor High School | Northolt | A rating |
| Islip Manor Medical Centre | Northolt | A rating |
| ISMAAEL CAR RENTAL LTD | Romford | A rating |
| ISMAIL CONVENIENCE STORE LTD | Manchester | A rating |
| Ismail Restaurants Ltd | wallington | A rating |
| ISMART APPS LIMITED | Glasgow | A rating |
| ISMART COMMUNICATIONS AND SERVICES LTD | Manchester | A rating |
| ISMART GIS LTD | London | A rating |
| ISMART RETAIL LIMITED T/A ISMART | Birmingham, England, | A rating |
| ISN Europe Limited | Huntingdon | A rating |
| ISN Software UK Ltd | London | A rating |
| ISO BUILD LTD | Bolton | A rating |
| ISO Design | Glasgow | A rating |
| ISO Sushi (Chapel Ash) Limited | Wolverhampton | A rating |
| ISO Sushi (Cheadle) Ltd | Stockport | A rating |
| ISO SUSHI STOURBRIDGE LTD | STOURBRIDGE | A rating |
| Isobel Advertising Ltd | London | A rating |
| Isochem Polyurethanes UK Limited | Newcastle upon Tyne | A rating |
| ISOFT PVT LTD | Manchester | A rating |
| ISOFT TESTING LTD | Solihull | A rating |
| Isogenica Ltd | Little Chesterford | A rating |
| Isogenix Limited | Oxford | A rating |
| ISOKINETICA LTD | London | A rating |
| Isola Bella Limited | Islington | A rating |
| Isoline Communications Limited | London | A rating |
| ISOMAB LTD | Cambridge | A rating |
| Isomer Capital LLP | London | A rating |
| Isomerase Therapeutics Limited | Cambridge | A rating |
| Isometric HQ Ltd | London | A rating |
| Isometrix Lighting & Design | LONDON | A rating |
| Isometrix Software UK Ltd | London | A rating |
| Isomi Projects Ltd | Runcorn | A rating |
| Isomorphic Labs Limited | London | A rating |
| ISON XPERIENCES UK LIMITED | LONDON | A rating |
| Isonets limited | Gatley | A rating |
| Isopol Consulting Limited | St Albans. Herts | A rating |
| Isotest Limited | Daventry | A rating |
| iSource Ltd | Watford | A rating |
| ISP MARKETING LTD | London | A rating |
| ISPSL 2031 LIMITED | London | A rating |
| Isquare Tech Solutions Ltd | Dartford | A rating |
| ISRA INSA | MANCHESTER | A rating |
| ISRA LIMITED T/A WOODSTOCK ROAD CHEMIST | OXFORD | A rating |
| Israeli Scouts Western Europe | London | A rating |
| ISRK LIMITED t/as MARIA'S FISH & KEBABS | LONDON | A rating |
| ISS Consultancy Ltd | BIRMINGHAM | A rating |
| ISS EHS UK LIMITED | LONDON | A rating |
| ISS UK LIMITED | Weybridge | A rating |
| ISSA MEDICAL CENTRE | PRESTON | A rating |
| Issey Miyake London Limited | London | A rating |
| ISSO RESTAURANTS UK LTD | London | A rating |
| ISSOS | Glasgow | A rating |
| ist power ltd | LEICESTER | A rating |
| ISTA ENERGY SOLUTIONS LIMITED | Duxford | A rating |
| ISTANBUL FILMMAKERS LTD | London | A rating |
| Istanbul Pizza House Ltd T/A Roosters Grill | Maidenhead | A rating |
| iStar Limited | Bromsgrove | A rating |
| Istari Global Limited | London | A rating |
| Istead Convenience Store Ltd | Gravesend | A rating |
| ISTENI CONSTRUCTIONS & CONSULTANTS LTD | Bristol | A rating |
| ISTIMAR LTD | London | A rating |
| Istituto Marangoni Ltd | London | A rating |
| ISTLONDON LEGAL LTD | London | A rating |
| ISTOBAL (UK) LTD | WORCESTERSHIRE | A rating |
| iStorage Limited | Perivale | A rating |
| Istrate Limited | Northampton | A rating |
| ISTVENTURES LTD | London | A rating |
| ISTYLE NW LTD | Bolton | A rating |
| ISUBC DIVING EQUIPMENT LTD | Blackpool | A rating |
| ISUN- IMMIGRATION SUPPORT NETWORK LTD | LONDON | A rating |
| ISUPERIOR CONSULTING LTD T/A Mooboo Bubble Tea | BRISTOL | A rating |
| iSupport Services Ltd | Huddersfield | A rating |
| ISUZU TRUCK (UK) LIMITED | HATFIELD | A rating |
| ISWARI BURROWS | London | A rating |
| ISX Financial UK Ltd | London | A rating |
| ISYSTANGO Limited | Croydon | A rating |
| iszwh Limited | Camberley | A rating |
| IT ACCESS LTD | Bolton | A rating |
| IT Autos Ltd | Birmingham | A rating |
| IT Big Bang Limited | Peterborough | A rating |
| IT CATERS LIMITED | BATH | A rating |
| IT CONNECTS LONDON LTD | Slough | A rating |
| IT CORPORATE LTD | Essex | A rating |
| IT Cube Ltd | Manchester | A rating |
| IT EHUB LIMITED | Slough | A rating |
| IT Europa Media & Intelligence Limited | Bucks | A rating |
| IT Global (UK) Limited | London | A rating |
| IT Global Consulting Limited | Slough | A rating |
| IT Governance Ltd | Ely | A rating |
| IT Helpdesk Burton Ltd | Burton on trent | A rating |
| IT HORIZONS LIMITED | London | A rating |
| IT Luggage | Hertford | A rating |
| IT MERGE LTD | Royston | A rating |
| IT MOBILITY LTD | Walsall | A rating |
| IT PROFESSIONAL TRAINING LTD | EDINBURGH | A rating |
| IT Retail Systems Ltd | Huddersfield | A rating |
| IT SERVICE LONDON LTD | London | A rating |
| IT Software Consultancy Services Limited. | Reading | A rating |
| IT Support Consultancy Ltd | Portsmouth | A rating |
| IT SYSTEM AND SERVICES LTD | London | A rating |
| IT TECHNOLOGY SOLUTION LTD | Leicester | A rating |
| IT Techwise Limited | London | A rating |
| IT TRANSMUTER CLOUD FORCE LIMITED | Bexleyheath | A rating |
| IT valley (London) Ltd | Egham | A rating |
| IT WHEEL LTD | London | A rating |
| IT YNR LTD | Feltham | A rating |
| IT-Logix Ltd | Stanmore | A rating |
| IT-SOHO LIMITED | London | A rating |
| It.com Domains Ltd | London | A rating |
| It's Bagels Soho | London | A rating |
| It's Fresh Limited | Burntwood | A rating |
| It's Not 1999Ltd T/A Locket | Harrow | A rating |
| IT'S PITA TIME LTD | London | A rating |
| IT@Spectrum Ltd | Hull | A rating |
| IT4Automation Ltd | Epsom | A rating |
| ITACHIO LIMITED | Ruislip | A rating |
| ITAD Limited | Brighton | A rating |
| ITAL BANGLA GROCERY SHOP LTD | London | A rating |
| Italia Conti Arts Centre Limited | Woking | A rating |
| Italia Fashion House Ltd | Bedford | A rating |
| ITALIA RESTAURANT LTD T/A VILLA VINCI | NEWCASTLE | A rating |
| Italian Aroma Coffee Co Ltd | Glasgow | A rating |
| ITALIAN CONNECTION LIMITED | BOSTON | A rating |
| ITALIAN CUISINI I.T RESTAURANT LTD | Swindon | A rating |
| Italian Dining Limited | Manchester | A rating |
| Italian in Edgware Ltd | Edgware | A rating |
| Italian Kitchen (Dorset) Ltd | Wareham | A rating |
| ITALIAN PIZZA AND PASTA LIMITED | London | A rating |
| Italian Style Ltd | Chiswick | A rating |
| Italian Treasures Ltd T/A Roberto Authentic Italian Gelato | York | A rating |
| Italiano Leicester Limited | Leicester | A rating |
| ITALIANO PIZZA & GRILL | BRADFORD | A rating |
| ITALIK STUDIO LTD | LONDON | A rating |
| ITALIKA LIMITED | London | A rating |
| Italo Pizza Lab Limited | Royal Tunbridge Wells | A rating |