Who has to charge VAT
VAT liability depends on turnover from supplies that are not excluded from the scope of the tax. Once the statutory threshold of CHF 100,000 per year is reached, or it is clear from the outset that it will be reached, the business must register with the Federal Tax Administration and receives a VAT number.
Below this threshold, voluntary registration remains possible. It can make sense when your customers are themselves VAT-registered and you incur costs subject to tax, less so when you mainly invoice private individuals.