Dear askaboutmoney, I am completing my tax returns for 2020. I have a non-PAYE income stream. Through a billing company, my clients are billed. Each year there can be up to a 20% difference to the amount that is billed to the money that is received for that tax year. Some invoices remain unpaid for many months and some are never paid. My question is this: do I pay tax on the actual money I receive in 2020 or how much is billed in 2020? Thanks in advance, A.