The National Health Insurance Levy - 2.5% charged on the value of most supplies, funding the NHIS.
Since the Value Added Tax Act 2025 (Act 1151) took effect on 1 January 2026, it is charged on the same base as VAT and the GETFund levy, and VAT-registered businesses can deduct it as input tax. Together the three come to 20%.
Before 2026 it was charged first, with GETFund and a COVID-19 levy since abolished, and VAT was then charged on top - which is why older explanations describe the levies as compounding.
This levy is also why NHIS membership costs so little at the point of registration — you have been paying for it all year, at every till.