Fees paid to your chamber are tax deductible. So long as it is analysed consistently, it doesn’t really matter how it's classified. For the tax return, if income is less than £85k (2019-20) it doesn’t get analysed out anyway; for those needing to show it on their tax return, I’d suggest putting it in either 'other office costs' or 'admin support' rather than 'professional subs' (which normally relates to membership of a professional body, rather than buying a specific service).
Liz Densley is medical specialist partner with Sussex Chartered Accountants, Honey Barrett, and is secretary of AISMA (the Association of Independent Specialist Medical Accountants). Contact her at email@example.com.