Overview

• October 5 is the registration deadline for first‑time filers who became self‑employed, started a business, or earned over £1,000 in untaxed income during the 2024/25 tax year.
• Missing registration can lead to failure‑to‑notify penalties ranging from 0% to 100% of tax due with interest, and late tax returns carry an automatic £100 fine that escalates the longer they are overdue.
• Paper Self Assessment returns are due by October 31, while online filing and payment of any tax owed are due by January 31, 2026.
• With interest rates around 5%, a basic‑rate taxpayer uses up the £1,000 Personal Savings Allowance at roughly £19,600 of savings, and a higher‑rate taxpayer at about £9,800.
• Analysts estimate 2.64 million people will pay tax on savings interest in 2025/26, with Treasury receipts from savings interest projected to exceed £6 billion.