| MJB Business Services Ltd ASP | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £2,750 |
| MJB Scheme | | | tax violations | 2017 | UK-HMRC | £47,192 |
| MJI Construction Limited | | | tax violations | 2019 | UK-HMRC | £23,672 |
| MJT Citrix Consultancy Limited | | | tax violations | 2023 | UK-HMRC | £24,849 |
| MK18 Limited ASP | | | anti-money-laundering deficiencies | 2022 | UK-HMRC | £6,400 |
| MM Builders Ltd | | | tax violations | 2023 | UK-HMRC | £190,457 |
| MM Swansea Ltd dba Mini Masala | | | tax violations | 2018 | UK-HMRC | £36,960 |
| MMA Financial Management Limited ASP | | | anti-money-laundering deficiencies | 2022 | UK-HMRC | £13,400 |
| MMO Limited | | | anti-money-laundering deficiencies | 2020 | UK-ICAEW | £7,040 |
| MMO Limited | | | accounting fraud or deficiencies | 2022 | UK-ICAEW | £3,450 |
| Mobilezone (UK) Limited | | | tax violations | 2016 | UK-HMRC | £25,466 |
| Modern Living Properties Ltd EAB | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £14,500 |
| Mojito Lounge Limited (The) dba Blueberry | | | tax violations | 2016 | UK-HMRC | £143,288 |
| Mold Elm Kebab Ltd | | | tax violations | 2023 | UK-HMRC | £113,332 |
| Monarch Commercial Limited EAB | | | anti-money-laundering deficiencies | 2022 | UK-HMRC | £3,500 |
| Moneemint Limited | | | tax violations | 2023 | UK-HMRC | £375,677 |
| Money Movers Ltd | | | anti-money-laundering deficiencies | 2021 | UK-HMRC | £0 |
| Moneywise IFA Limited | | | investor protection violation | 2010 | UK-FSA | £19,600 |
| Monifieth Car Wash | | | tax violations | 2017 | UK-HMRC | £19,057 |
| Monkmoor Bathrooms Ltd | | | tax violations | 2023 | UK-HMRC | £53,689 |
| Mono Manchester Ltd | | | tax violations | 2017 | UK-HMRC | £67,376 |
| Monter Limited | | | tax violations | 2016 | UK-HMRC | £266,766 |
| Montgomery Taff Ltd | | | accounting fraud or deficiencies | 2020 | UK-ICAEW | £350 |
| Montrose Food & Wine Limited | | | tax violations | 2018 | UK-HMRC | £17,156 |
| Mookys Print and Design Ltd | | | tax violations | 2022 | UK-HMRC | £147,923 |
| Moonlight Curtains and Interior Design Limited | | | tax violations | 2018 | UK-HMRC | £20,412 |
| Moonlight Pharmacy Ltd. | | | tax violations | 2016 | UK-HMRC | £18,673 |
| Moore | | | accounting fraud or deficiencies | 2017 | UK-ICAEW | £5,000 |
| Moore and Smalley LLP | | | accounting fraud or deficiencies | 2024 | UK-ICAEW | £6,650 |
| Moore Family Office Limited | | | accounting fraud or deficiencies | 2021 | UK-ICAEW | £700 |
| Moore Kingston Smith LLP | | | accounting fraud or deficiencies | 2020 | UK-ICAEW | £5,745 |
| Moore Kingston Smith LLP | | | accounting fraud or deficiencies | 2019 | UK-ICAEW | £0 |
| Moore Kingston Smith LLP | | | accounting fraud or deficiencies | 2018 | UK-ICAEW | £19,724 |
| Moore Kingston Smith LLP | | | accounting fraud or deficiencies | 2018 | UK-ICAEW | £4,218 |
| Moore Kingston Smith LLP | | | accounting fraud or deficiencies | 2023 | UK-ICAEW | £28,358 |
| Moore Scarrott Limited | | | accounting fraud or deficiencies | 2022 | UK-ICAEW | £2,795 |
| Moore Stephens (NI) LLP | | | accounting fraud or deficiencies | 2016 | UK-FRC | £140,000 |
| Moosa Retail 2 Limited, formerly franchise of Pepe's Piri Piri | | | tax violations | 2022 | UK-HMRC | £36,663 |
| More Booze Ltd | | | tax violations | 2018 | UK-HMRC | £59,469 |
| More Hair & Beauty | | | tax violations | 2018 | UK-HMRC | £22,722 |
| More Than Just Admin Limited ASP | | | anti-money-laundering deficiencies | 2022 | UK-HMRC | £2,543 |
| Morelli's | | | tax violations | 2024 | UK-HMRC | £12,175 |
| Morgan & Sons Estate Agents Ltd EAB | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £7,000 |
| Morgan Alexander Estates Limited EAB | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £2,750 |
| Morgan H Lewis Limited EAB | | | anti-money-laundering deficiencies | 2022 | UK-HMRC | £1,450 |
| Morgan Martin (LANCS) Limited EAB | | | anti-money-laundering deficiencies | 2022 | UK-HMRC | £6,739 |
| Morley Fencing & Landscaping Ltd | | | tax violations | 2018 | UK-HMRC | £19,682 |
| Morley Road Nursery Ltd | | | tax violations | 2018 | UK-HMRC | £36,896 |
| Mortgage & Property Plus Limited EAB | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £4,500 |
| Morton Chater Solicitors | | | anti-money-laundering deficiencies | 2023 | UK-SRA | £2,600 |
| Mos Services Mid Ltd | | | tax violations | 2022 | UK-HMRC | £647,422 |
| Mosley & Company | | | investor protection violation | 2012 | UK-FSA | £10,500 |
| Moss Taverns Ltd dba The Holly Bush | | | tax violations | 2016 | UK-HMRC | £52,450 |
| Motopro | | | tax violations | 2024 | UK-HMRC | £43,281 |
| Mounsey Surveyors Limited ASP | | | anti-money-laundering deficiencies | 2022 | UK-HMRC | £10,007 |
| Move Holmes Limited EAB | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £4,500 |
| Move2Here Limited EAB | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £2,750 |
| MoveAction Limited AMP | | | anti-money-laundering deficiencies | 2022 | UK-HMRC | £10,000 |
| Moy Auto Services | | | tax violations | 2017 | UK-HMRC | £41,702 |
| MP Food & Wine/J&M News | | | tax violations | 2018 | UK-HMRC | £289,280 |
| Mpower4u Limited | | | tax violations | 2017 | UK-HMRC | £37,409 |
| Mr Food Design Limited | | | tax violations | 2019 | UK-HMRC | £232,482 |
| Mr Q Chinese Takeaway | | | tax violations | 2023 | UK-HMRC | £81,735 |
| MSA Group (UK) Ltd | | | tax violations | 2021 | UK-HMRC | £67,981 |
| MSK 9 Limited EAB | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £2,750 |
| Mslon Ltd | | | tax violations | 2023 | UK-HMRC | £132,621 |
| MSR Partners LLP | | | accounting fraud or deficiencies | 2019 | UK-ICAEW | £455,813 |
| MSR Partners LLP | | | accounting fraud or deficiencies | 2019 | UK-ICAEW | £30,693 |
| MSW Consultants Limited | | | tax violations | 2023 | UK-HMRC | £24,047 |
| MT Global Ltd | | | anti-money-laundering deficiencies | 2021 | UK-HMRC | £1,994,007 |
| MT Global Ltd | | | anti-money-laundering deficiencies | 2020 | UK-HMRC | £0 |
| MTQ Estates Private Limited EAB | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £2,750 |
| Mubinelectrics Ltd | | | tax violations | 2024 | UK-HMRC | £98,326 |
| Mude Ltd dba Big Chef Cafe & Restaurant | | | tax violations | 2018 | UK-HMRC | £76,775 |
| MUFG Securities EMEA plc | Mitsubishi UFJ Financial Group | financial services | internal controls deficiency | 2017 | UK-PRA | £8,925,000 |
| Multi MD Limited | | | tax violations | 2021 | UK-HMRC | £76,910 |
| Mumbai Junction Ltd | | | tax violations | 2019 | UK-HMRC | £626,462 |
| Mumtaz Food Products Ltd | | | tax violations | 2023 | UK-HMRC | £40,938 |
| Muranda Electrical Services Ltd | | | tax violations | 2020 | UK-HMRC | £499,203 |
| Muras Baker Jones Limited | | | accounting fraud or deficiencies | 2023 | UK-ICAEW | £3,656 |
| Murdock & Wasley Estate Agents Ltd EAB | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £13,600 |
| Murry Harcourt Limited | | | accounting fraud or deficiencies | 2019 | UK-ICAEW | £1,072 |
| Mustafa&Co Property Management Ltd EAB | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £4,500 |
| MVF South Shields Limited dba Man V Food | | | tax violations | 2018 | UK-HMRC | £15,308 |
| My Favourite Chicken Ltd dba Sopranos | | | tax violations | 2021 | UK-HMRC | £49,185 |
| My Sales Limited EAB | | | anti-money-laundering deficiencies | 2022 | UK-HMRC | £3,561 |
| MY.KLT Ltd | | | tax violations | 2018 | UK-HMRC | £2,713,705 |
| Myers Clark Limited | | | accounting fraud or deficiencies | 2017 | UK-ICAEW | £5,980 |
| Myint Construction Ltd | | | tax violations | 2021 | UK-HMRC | £28,772 |
| Myrings Estate Agents Ltd EAB | | | anti-money-laundering deficiencies | 2023 | UK-HMRC | £15,600 |
| N T Accountancy Services Limited ASP | | | anti-money-laundering deficiencies | 2022 | UK-HMRC | £4,455 |
| N&M Paradise Ltd | | | tax violations | 2024 | UK-HMRC | £107,137 |
| N-Hanced LLP | | | investor protection violation | 2010 | UK-FSA | £21,000 |
| N.S. Amin & Co | | | accounting fraud or deficiencies | 2019 | UK-ICAEW | £1,000 |
| N9 Beijing Limited formerly trading as Chef Beijing | | | tax violations | 2023 | UK-HMRC | £71,422 |
| Nachi Ltd | | | tax violations | 2019 | UK-HMRC | £329,505 |
| Nafeez Takeaway | | | tax violations | 2016 | UK-HMRC | £42,613 |
| Nahid Residential Limited | | | tax violations | 2020 | UK-HMRC | £118,956 |
| Nail Express | | | tax violations | 2019 | UK-HMRC | £13,615 |
| Nails & Beauty Limited | | | tax violations | 2020 | UK-HMRC | £48,480 |
| Nails@555 Limited fka Nails @5 Limited | | | tax violations | 2023 | UK-HMRC | £116,981 |
