The UK tax authority has announced that Self Assessment customers have 100 days remaining to submit their tax return for the 2025–2026 tax year and pay any taxes due. Self Assessment is a system used to collect income tax from individuals whose income is not taxed automatically, including the self-employed, sole traders, and those with additional sources of income. Taxpayers are advised not to delay submitting their return until the last moment to avoid technical failures, completion errors, and potential late payment penalties. Timely submission also allows taxpayers to plan their budget for paying tax in advance and, if necessary, request a payment plan. The tax authority traditionally reminds taxpayers of the approaching deadline in advance, emphasizing the importance of preparing necessary documents—information about income, expenses, and allowances—well in advance. Late submission of a return or failure to pay tax on time may result in financial penalties, the amount of which depends on the length of the delay. The Self Assessment system affects millions of taxpayers in the UK annually, and the authority continues to improve online services to simplify the tax return submission process.