Making Tax Digital for VAT is compulsory. The other stages will also be compulsory when fully added, such as MTD for income tax. The only way to opt out is if you fit into the list of exemptions, which generally includes people who can't use a computer or online services to file taxes. You cannot opt out of the MTD for VAT threshold once you pass it. If your small business hits the VAT threshold, then you need to start filling out your VAT returns through compatible software and devices.