At Arendelle, many new clients ask us the same question: “Why can’t I just keep using my spreadsheets?” It’s understandable—spreadsheets have been the go-to tool for managing finances for years. But with Making Tax Digital (MTD) for Income Tax starting from April 2026, spreadsheets will no longer be enough for most self-employed people and landlords. Below, we explain why spreadsheets are becoming obsolete and how the changes will affect your Self Assessment tax returns