As the leaves begin to turn gold and amber, the autumn months bring more than just a change in the weather. For individuals and businesses across the UK, this time of year also signals a crucial period of financial preparation, especially with the self-assessment season looming. At GW Accountants, we understand that between advancing business activity, planning for the festive period, and managing everyday finances, tax matters can be a source of stress. That’s why autumn is the ideal moment to take stock, get organised and ensure you’re in the best possible position before the year draws to a close.

In this blog, we’ll present practical guidance on autumn financial planning, from key self-assessment deadlines to how to file online via HMRC’s service, plus helpful tips on avoiding common problems. Whether you’re self-employed, a landlord, a company director or have other sources of untaxed income, this is your friendly reminder to take action now. And if you’re feeling uncertain or overwhelmed, GW Accountants is here to help.

The Autumn Transition: From Summer to Financial Focus

For many, the period from late September through to December marks a shift from the more relaxed summer months into a phase of re-focusing. Business routines resume in full, new financial quarters begin and for many, the need to review expenses, income and tax strategy becomes more pressing.

Autumn offers a chance to tidy up your books, reconcile invoices and receipts and begin the steps towards filing your self-assessment with confidence. By starting in the autumn rather than leaving everything until the new year, you’re giving yourself time to:

• Identify missing records or receipts well ahead of any deadlines;
  
• Understand your likely tax position and start budgeting accordingly;
  
• Spot opportunities to simplify or optimise your affairs (for example allowable expenses or reliefs);
  
• Avoid the rush and last-minute stress that so many experience in January.
  

At GW Accountants, we recommend that clients begin their preparation in the autumn, ideally by the end of November, so that when January comes, everything is in place.

Self-Assessment: What You Need to Know This Season

If you’re required to complete a self-assessment tax return, for example because you’re self-employed, receive rental income, or have other untaxed income, then you’ll be using HMRC’s online service to file your return. According to HMRC’s guidance, you can file your tax return anytime on or after 6 April following the end of the tax year.

It’s important to meet the deadlines, because if you don’t send your return by the deadline you’ll face a penalty. 

Here are the key steps and requirements for the online self-assessment service:

• You’ll need to sign-in to HMRC’s service. If you don’t already have log-in details, you’ll be able to create them.
  
• You’ll need your Unique Taxpayer Reference (UTR) number.
  
• You don’t have to complete the whole return in one go, you can save your entries and return later.
  
• For identity verification, HMRC may require you to provide proof of identity (for example passport or driving licence) when you sign-in.
  
• Note: some categories cannot use the standard online service (for example certain trusts, estates or partnership returns).
  

Key Deadlines to Bear in Mind

While the online service opens early in the tax year, the real deadline to watch is 31 January for online returns and payments. While HMRC’s page doesn’t list all deadlines on that page, in practice you should keep the following in mind:

• For paper returns: 31 October after the end of the tax year.
  
• For online returns: 31 January after the end of the tax year (for example, for 2024/25 you’d file by 31 January 2026).
  
• First-time filers or those who have not submitted returns before: you’ll need to register for self-assessment (often by 5 October of the tax year if you’re newly liable).
  

Missing the deadline can lead to automatic penalties, even if you owe no tax, you could face a fine for late filing.

By beginning your preparation in the autumn, you give yourself the best chance of filing early or at least submitting well ahead of the deadline, reducing stress and risk of penalty.

Getting Organised: What You’ll Need

Whether you’re completing your return yourself or working with GW Accountants, good preparation improves accuracy and reduces surprises. Here’s a checklist to guide you:

Personal details and registration:

• Ensure you have your UTR (Unique Taxpayer Reference).
  
• Update your personal details if you’ve changed address, name or employment status.
  

Income and earnings:

• For self-employed: invoices, sales records, business income.
  
• For employment: P60, P45, or P11D as relevant.
  
• Additional income: rentals, dividends, interest, other untaxed income.
  
• Bank interest, investment income.
  

Expenses and deductions:

• Business expenses (travel, office supplies, professional subscriptions).
  
• Pension contributions, charitable donations (for tax relief).
  
• Investment disposal records (capital gains/losses).
  

Digital tools:

• Consider using compatible accounting software in line with the Making Tax Digital regime (if applicable).
  
• Keep electronic copies of receipts, records and statements for ease of retrieval.
  

Even if you’re comfortable with bookkeeping, it’s wise to review and reconcile your records in the autumn rather than waiting for the deadline.

Avoiding Common Self-Assessment Mistakes

Many taxpayers seek help because they’ve faced penalties or queries from HMRC. The good news is many mistakes are avoidable with care:

• Missing the deadline – Even one day late on the return can trigger a penalty.
  
• Incorrect or incomplete figures – Typos, rounding errors, overlooked income.
  
• Failing to register when required – If you’ve never submitted a return before, you must register for self-assessment before filing.
  
• Claiming ineligible expenses – Not all costs associated with your work or business are allowable; incorrect claims may result in HMRC adjusting your return.
  
• Poor record-keeping – HMRC can ask for evidence of your entries for up to six years.
  
• Assuming you don’t need to file – Even if you think you don’t owe tax, you may still be required to submit a return, especially if you have untaxed income (rental, dividends, etc.).
  

At GW Accountants we review returns with these common pitfalls in mind,  ensuring you’re accurate, compliant and best positioned to avoid problems.

Maximising Tax Efficiency in Autumn

Autumn presents an opportunity to review your position and implement strategies that could reduce your tax liability or improve financial clarity. Some tips to consider:

• If you’re self-employed or running a small business, review your income, expenses and potential investment plans (for example, whether you might benefit from the Annual Investment Allowance).
  
• Pension contributions made before the end of the tax year can reduce your taxable income.
  
• Ensure you’ve utilised your ISA allowance (and other tax-efficient vehicles) where applicable.
  
• Review any capital gains or planned disposals, autumn is a good time to assess whether realising gains or losses before 5 April is beneficial.
  
• Consider your cash flow and plan for a tax-bill reserve so that by 31 January you’re not caught short.
  

These are broad suggestions, your personal or business situation may need more tailored advice. That’s where we at GW Accountants are ready to help.

Digital Tools and the Move to Making Tax Digital

More and more businesses are adapting to digital tools and software for bookkeeping and tax compliance. While the standard self-assessment service for individuals remains available, for businesses and self-employed traders the move towards digital reporting via Making Tax Digital (MTD) means early adoption is wise.

Using modern, compliant software (such as Xero, QuickBooks, FreeAgent or equivalent) helps you:

• Keep your records updated in real-time;
  
• Store receipts and documentation electronically;
  
• Minimise manual errors when you come to file your return;
  
• Simplify the interaction with HMRC’s online services for tax returns and payments.
  

If you haven’t yet adopted digital bookkeeping or want to review whether your systems are compliant and efficient, now is the time. At GW Accountants we can support you with software selection, setup and ongoing support, easing the burden of transition.

The Benefits of Early Autumn Planning

By starting your review and preparation this autumn, you gain several advantages:

• Peace of mind knowing you’re ahead of the curve rather than racing towards the deadline.
  
• Better cash flow planning, with more time to budget for tax bills, capital expenditures or investments.
  
• Time to explore strategic options, like tax reliefs, pension top-ups or business investments, instead of knock-on panic.
  
• Reduced risk of errors, missing documents or oversight because you’ve given yourself breathing room.
  
• Improved clarity — when the festive season arrives, you’ll be better positioned to handle business and personal finances without added tax stress.
  

How GW Accountants Can Help

Whether you’re completing your self-assessment return, managing your small business accounts, or simply want expert guidance through an increasingly complex tax environment, our team at GW Accountants is ready to support you across the UK.

Our services include:

• End-to-end self-assessment support — ensuring you meet all the HMRC requirements, deadlines and compliance standards.
  
• Business tax planning and forecasting — tailored to your objectives and helping you optimise outcomes.
  
• Digital bookkeeping and software support — guiding you through the transition to compliant and efficient systems.
  
• Year-end planning and strategy sessions — helping you make the most of the autumn period to prepare for the year ahead.
  
• Friendly, proactive advice — not just reacting to deadlines, but planning ahead with you as a partner in your success.
  

If you’re feeling overwhelmed by your accounting obligations, uncertain about your tax return, or simply want a second opinion on your finances, please reach out. A quick conversation could save you time, reduce stress and potentially improve your outcomes.

Final Thoughts

Autumn is a season of change, and that applies as much to our financial lives as to the natural world. It’s a time to reflect, plan and position yourself for success. By getting on top of your finances now and using the autumn months to best effect, you’re setting yourself up for a smoother journey into the new year.

And remember: you don’t have to go it alone.

If you’re planning your self-assessment, reviewing your business finances, or just want expert support to make sure you’re on the right path, GW Accountants is here for you. Reach out today for a friendly, professional chat and let’s make this autumn your most organised and financially confident yet.