The VPD applies two tax bands: £2 per 10ml of nicotine-containing e-liquid, and £0.30 per ml for nicotine-free products. To calculate the tax on a single purchase line, multiply the volume by the rate and add it to your wholesale cost.
Example: A box of 10 x 10ml nicotine salt at 20mg/ml. Tax = 10 bottles x £2.00 = £20.00. Add this to your wholesale cost per box to get the true landed cost. This number should be the basis for your retail price calculation.
TrackElf recommends recalculating your margin on every affected SKU, as the tax shifts the cost structure more sharply on smaller bottle sizes. A 10ml nic salt that cost £2.20 wholesale may now cost £4.20 after VPD, meaning your retail price needs to increase by at least £1.50 to maintain margin.