With a 20% VAT rate, I buy something at 1.20 (1 + 0.20 VAT). So in effect I paid 0.20 as tax. Then I sell it at 1.80 (1.50 + 0.30 VAT). So I have collected 0.30

With a 20% VAT rate, I buy something at 1.20 (1 + 0.20 VAT). So in effect I paid 0.20 as tax. Then I sell it at 1.80 (1.50 + 0.30 VAT). So I have collected 0.30 as tax. But I do not pass on all of the 0.30 tax to the government, I subtract the 0.20 I have already paid as VAT, and give the government 0.10. In effect, the consumer has paid the 0.30 VAT on the final price of 1.50 excluding VAT. I find the definitions in the investopedia link you provided very confusing.