What to know before you decide
Eye examinations and optical goods are not the same supply
Qualifying professional eye-care services may be exempt, while spectacles and other goods are normally taxable. Mixed charges need an appropriate and supportable split under the applicable rules. Partial exemption may affect recovery of VAT on shared overheads. A reliable sales system should preserve the distinction rather than putting every receipt through one code.
Keep stock and locum income visible
An owner needs stock values, supplier rebates and credit notes alongside clinical income; a locum needs contracts, receipts and evidence of allowable costs. These are different accounting workflows. For owners, monitor gross margins separately from appointment revenue. For locums, compare amounts invoiced, deductions made and cash received before estimating tax.