Processing on behalf of others is a taxable service. Pay VAT according to income excluding tax (income including tax/1.03). You are a small-scale taxpayer with a tax rate of 3%. In addition, you have to pay urban construction tax (7% or 5% or 1%, depending on the location, the tax rate is different), education surcharge (3%), local education surcharge (2% or 1%) and stamp duty (0.03% of income) at the local tax bureau.