First, you need to add a category to all of your transactions – and if you’re VAT registered, you’ll  also need to add VAT rates. When you do this, Tide Accounting automatically matches these categories to HMRC’s Self Assessment SA103 Business Income and Business Expenses categories. This is how we provide your Self Assessment estimate – but please note, the estimate is only based on the transactions in your Tide account and any manual transactions you’ve added.