Key Accounting Dates for October 2025

/Published:24th September 2025/inAccounting Wise, News, Tax
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October is a busy month for UK businesses when it comes to tax and compliance. From Corporation Tax payments and returns to Self Assessment notifications, PAYE, CIS, and even Plastic Packaging Tax, there are several key deadlines that business owners need to keep firmly on their radar.

Missing a filing or payment date can lead to HMRC penalties and unnecessary stress but with a little forward planning, you can stay ahead. In this guide, we’ve highlighted the most important UK accounting deadlines for October 2025, along with practical tips and reminders to help you prepare.

01/10/25 – Corporation Tax payment: 31 December 2024 year ends

If your company’s financial year ended on 31 December 2024, the deadline to pay your Corporation Tax is 1 October 2025.

Who this applies to:

  • Limited companies with accounting periods ending on 31 December 2024.
  • Companies that don’t qualify for quarterly instalment payments (usually only very large businesses).

Tips to stay on top of it:

  • Double-check your Corporation Tax liability using HMRC’s Company Tax Return service.
  • If cash flow is tight, plan ahead HMRC’s Time to Pay arrangements may be an option, but you must apply before the deadline.
  • Consider setting up a Direct Debit for Corporation Tax to reduce the risk of missing deadlines.

Resource reminder:

  • Make sure your CT600 (Company Tax Return) has already been filed or is in progress the filing deadline is later (12 months after year end), but having the return ready makes paying the correct tax easier.
  • Cloud accounting software like Balance App or QuickBooks can help you forecast tax liabilities earlier in the year, so you’re not caught off guard.

05/10/25 – Self Assessment: notify HMRC of 2024-25 Chargeability

If you had untaxed income in 6 April 2024–5 April 2025 and haven’t sent a Self-Assessment return before, you must tell HMRC by 5 October 2025 by registering for Self-Assessment.

Who this applies to (common cases):

  • New sole traders/self-employed in 2024/25.
  • Individuals with rental income, significant savings/dividends, capital gains, foreign income, or High-Income Child Benefit Charge, who weren’t already filing.
  • Partners in a partnership (partners register too).
    Tell HMRC by registering online; HMRC’s tool guides the right route (self-employed, not self-employed, partner, etc.).

Practical tips:

  • Leave time for your UTR & activation code. HMRC says your UTR usually arrives by post in ~15 days (longer if overseas), and non-self-employed registrations say around 21 days for a response. Don’t cut it fine.
  • If you register after 5 Oct, HMRC may give you a different filing deadline (3 months from their notice) but it’s safer to register by 5 Oct to avoid penalties and login delays.
  • New sole traders should also make sure Class 2/4 NIC is set up correctly when registering.

How to do it (quick routes):

Why it matters:
HMRC expects “notification of chargeability” by 5 October so they can issue the return in time for the normal cycle. Missing it can trigger failure-to-notify penalties and squeezes your time to file/pay.

07/10/25 – VAT return submission and payment (online): month or quarter-end 31 August 2025

If your VAT accounting period ended on 31 August 2025, your VAT return and payment are both due by 7 October 2025 (when filing online).

Who this applies to:

  • All VAT-registered businesses with monthly or quarterly periods ending 31 August 2025.
  • Most businesses must file through Making Tax Digital (MTD) compatible software, not the old HMRC portal.

Tips to avoid last-minute stress:

  • Reconcile early. Check your bookkeeping is up to date, and ensure all invoices and receipts for the period are captured.
  • Use MTD software. Platforms like Xero, QuickBooks, or FreeAgent connect directly with HMRC’s system, helping reduce errors.
  • Plan for payment clearance. If paying by direct debit, HMRC collects it automatically but if paying via bank transfer or card, allow a couple of days for funds to clear.
  • If cash flow is tight, HMRC offers a Time to Pay arrangement, but you need to set it up before the deadline.

Helpful reminder:

Penalty note:

  • Late filing or payment may result in interest charges and penalties under HMRC’s new points-based VAT penalty system introduced in 2023.

14/10/25 – CT61: return and payment for the quarter ended 30 September 2025

If your company made certain payments between 1 July and 30 September 2025, such as loan interest, certain royalties, or payments to non-UK residents, you may need to file a CT61 return and pay the tax withheld by 14 October 2025.

Who this applies to:

  • UK companies that deduct Income Tax at source on payments like interest, alternative finance returns, and certain annual payments.
  • It does not apply to all companies only those that have made payments requiring withholding under HMRC rules.

Tips to stay compliant:

  • Check your obligations early. Many businesses overlook CT61 because it only applies in specific situations but HMRC expects a return even if no tax is due (nil return).
  • Use the official CT61 form. It can be ordered from HMRC or filed online in some cases.
  • Keep records tidy. Cross-check any interest or royalty payments against your accounting software so you don’t miss anything.

Resource reminder:

  • Guidance on when CT61 applies and how to complete it is available on HMRC’s website under Company Tax: CT61 returns.
  • If unsure, speak to your accountant it’s better to confirm whether CT61 applies than risk missing a deadline.

Penalty note:

  • Late filing or payment can lead to interest on unpaid tax and potential HMRC penalties.

19/10/25 – PAYE, NIC and CIS payment (postal): month-end 5 October 2025

If you pay your employees or subcontractors, any PAYE, National Insurance Contributions (NICs), and Construction Industry Scheme (CIS) deductions for the period 6 September to 5 October 2025 must reach HMRC by 19 October 2025 if paying by post (cheque).

Who this applies to:

  • All employers operating PAYE schemes.
  • Contractors deducting CIS tax from subcontractors.

Tips for smooth payment:

  • Allow extra time. Postal payments must clear by the 19th, not just be sent factor in delivery time.
  • Switch to electronic payments if possible, as they’re faster, more reliable, and give you an extra 3 days (deadline 22 October).
  • If paying by cheque, make it payable to ‘HM Revenue and Customs only’ and include your Accounts Office reference.

Resource reminder:

  • HMRC provides detailed instructions on how to pay PAYE, NIC and CIS, including different payment methods, in your Business Tax Account.

Penalty note:

  • Payments received after the deadline may lead to late payment penalties and daily accruing interest.

19/10/25 – PAYE, NIC and CIS payment (postal): quarter-end 5 October 2025

If you’re an employer or contractor making quarterly rather than monthly PAYE payments, your payment covering 6 July to 5 October 2025 must reach HMRC by 19 October 2025 when paying by post (cheque).

Who this applies to:

  • Smaller employers who are allowed to pay PAYE and NIC quarterly instead of monthly.
  • Contractors who report and pay CIS deductions

Tips for staying on top of it:

  • Check if you qualify for quarterly payments. Generally, you can only pay quarterly if your average monthly PAYE/NIC liability is under £1,500.
  • Don’t rely on postal times. HMRC must receive and clear the cheque by the 19th — aim to send it at least a few working days before.
  • Use your Accounts Office reference. Write it on the back of the cheque to ensure its allocated correctly.

Resource reminder:

  • Full guidance on PAYE payment deadlines and how to pay can be found through HMRC’s employer help pages.
  • If you use online payroll software, it should automatically calculate what’s due for the quarter.

Penalty note:

  • Late quarterly payments attract the same interest and penalty regime as monthly PAYE repeated late payments can escalate charges.

19/10/25 – PAYE settlement agreement: payment of 2024-25 Class 1B NIC and tax (postal)

If you hold a PAYE Settlement Agreement (PSA) with HMRC, the deadline to pay the tax and Class 1B National Insurance due for the 2024/25 tax year is 19 October 2025 when paying by post (cheque).

What a PSA covers:

  • Items that are minor, irregular, or impractical to tax through payrollg. staff entertaining, small gifts, or non-cash benefits.
  • Instead of deducting tax/NIC from employees, the employer pays the liability in one go.

Who this applies to:

  • Employers who applied for and agreed a PSA with HMRC for the 2024/25 tax year.
  • The agreement must have been in place by 5 July 2025 to be valid.

Tips to manage the deadline:

  • Check your PSA calculation early. It must include the grossed-up tax and Class 1B NICs.
  • Don’t leave posting late. HMRC must receive and clear your cheque by the 19th — so post several days in advance.
  • Consider switching to electronic payments. This gives you until 22 October 2025 and reduces the risk of postal delays.

Resource reminder:

  • HMRC provides step-by-step guidance on how to calculate and pay PSA liabilities through the employer section of its website.
  • Keep clear records PSA items should not also appear on P11Ds or payroll submissions.

Penalty note:

  • Late payments will attract interest and potential penalties, and HMRC may revoke your PSA if deadlines are repeatedly missed.

19/10/25 – CIS return: payments made to subcontractors in the month to 5 October 2025

If you’re a contractor operating under the Construction Industry Scheme (CIS), you must file your monthly CIS return by 19 October 2025. This return covers all payments made to subcontractors between 6 September and 5 October 2025.

Who this applies to:

  • Contractors who pay subcontractors for construction work in the UK.
  • This includes companies, partnerships, and self-employed individuals registered as CIS contractors.

What’s required:

  • Report all subcontractor payments and the tax you’ve deducted (if applicable).
  • Even if you haven’t paid any subcontractors this month, you still need to file a nil return unless HMRC has told you otherwise.

Tips to stay compliant:

  • Use HMRC’s CIS Online service or your payroll software to submit returns quickly.
  • Double-check subcontractor details (UTR, verification status) to avoid filing errors and incorrect deductions.
  • Don’t forget payment. Any CIS tax deducted must be paid to HMRC by the same date as your PAYE/NIC deadline.

Resource reminder:

  • You can manage CIS returns via your HMRC Business Tax Account or through compatible payroll/accounting software.
  • HMRC provides a CIS deductions statement template useful for giving subcontractors their monthly statements.

Penalty note:

  • Late CIS returns incur automatic fixed penalties (starting at £100), with escalating charges if the return is more than 2, 6, or 12 months overdue.

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22/10/25 – PAYE, NIC and CIS payment (electronic): month-end 5 October 2025

If you’re paying PAYE, National Insurance Contributions (NICs), and Construction Industry Scheme (CIS) deductions electronically for the period 6 September to 5 October 2025, your payment must clear HMRC’s account by 22 October 2025.

Who this applies to:

  • All employers operating PAYE schemes.
  • Contractors making CIS deductions.
  • This is the electronic payment deadline, which gives you 3 extra days compared to the postal deadline (19 October).

Tips for smooth payment:

  • Check your cut-off times. Online banking, CHAPS, Bacs, and Faster Payments all have different clearance times. Don’t assume same-day transfers will always clear in time.
  • Use the correct reference. Always quote your 13-character Accounts Office reference so the payment is allocated properly.
  • Set up a Direct Debit with HMRC. This ensures payments are taken automatically on the correct date, helping you avoid interest or penalties.

Resource reminder:

  • HMRC’s How to pay PAYE guidance explains accepted electronic methods and clearance times.
  • Most payroll software now integrates with HMRC, so you can pay and report in one workflow.

Penalty note:

  • Missing the 22 October deadline may result in late payment penalties and daily accruing interest.

22/10/25 – PAYE, NIC and CIS payment (electronic): quarter-end 5 October 2025

If you’re approved to make quarterly PAYE payments, your payment covering 6 July to 5 October 2025 must reach HMRC by 22 October 2025 when paying electronically.

Who this applies to:

  • Employers with a monthly PAYE/NIC liability averaging under £1,500, who have HMRC’s agreement to pay quarterly instead of monthly.
  • Contractors paying over CIS deductions on a quarterly basis.

Tips to keep on track:

  • Plan cash flow early. Quarterly liabilities can be larger, so build the payment into your forecasts.
  • Use secure electronic methods. Faster Payments, CHAPS, or Bacs are all acceptable just check clearance times with your bank.
  • Double-check your Accounts Office reference. A mistyped reference can delay allocation and still trigger late-payment interest.
  • If your payroll software produces a summary, match it against your Business Tax Account before submitting the payment.

Resource reminder:

  • HMRC’s employer guidance on PAYE payment deadlines confirms the differences between monthly and quarterly schedules.
  • Many payroll systems will flag if you qualify for quarterly PAYE, so check your settings are correct.

Penalty note:

  • Missing the 22 October deadline risks interest and late-payment penalties and repeated lateness can mean HMRC removes quarterly payment privileges.

22/10/25 – PAYE settlement agreement: payment of 2024-25 Class 1B NIC and tax (electronic)

If you hold a PAYE Settlement Agreement (PSA) with HMRC, the deadline to pay the tax and Class 1B NIC due for the 2024/25 tax year is 22 October 2025 when paying electronically.

Who this applies to:

  • Employers with an agreed PSA in place for 2024/25 (applied for by 5 July 2025).
  • Businesses using a PSA to cover items that are minor, irregular, or impractical to put through payroll (e.g. staff entertaining, small benefits, non-cash gifts).

Tips to make payment hassle-free:

  • Calculate early. Your PSA covers both grossed-up tax and Class 1B NIC double-check your figures well before the deadline.
  • Use electronic payments wisely. Faster Payments and CHAPS usually clear the same or next working day, while Bacs can take three days. Don’t cut it too close.
  • Quote the right reference. Use your PAYE Accounts Office reference so HMRC allocates the payment correctly.
  • Keep PSA records safe. Ensure benefits included in your PSA are not duplicated on P11Ds or payroll records.

Resource reminder:

  • Guidance on how to pay your PSA and calculate liabilities is available in the employer section of HMRC’s website.
  • Accounting software or spreadsheets can help you track PSA items throughout the year instead of rushing at year-end.

Penalty note:

  • Missing the 22 October electronic deadline could result in interest charges and late-payment penalties, and HMRC may reconsider future PSA approvals if deadlines are repeatedly missed.

30/10/25 – Non-resident landlord scheme: payment of tax for the quarter ended 30 September 2025

If you operate under the Non-Resident Landlord (NRL) Scheme, any tax deducted from rental income between 1 July and 30 September 2025 must be paid to HMRC by 30 October 2025.

Who this applies to:

  • Letting agents managing UK rental property for landlords based overseas.
  • Tenants paying rent directly to a non-resident landlord, if no letting agent is involved.
  • Non-resident landlords themselves, if HMRC hasn’t approved rental income to be paid gross.

What’s required:

  • Send the deducted tax to HMRC by the deadline.
  • Provide landlords with a deduction certificate (NRL6) annually (by 5 July following the tax year).

Tips for compliance:

  • Mark your calendar quarterly. NRL payments are due on 30 January, 30 April, 30 July, and 30 October each year.
  • Use electronic payment where possible. It’s faster, more reliable, and avoids postal delays.
  • Keep detailed records. Track gross rent received, tax deducted, and payments made this supports both HMRC reporting and certificates to landlords.

Resource reminder:

  • Full guidance is available in HMRC’s Non-Resident Landlord Scheme manual.
  • If a landlord has HMRC approval to receive rent gross, no tax needs deducting but you must keep their approval letter on file.

Penalty note:

  • Late or missing payments can result in interest charges, penalties, and compliance checks by HMRC.

31/10/25 – Plastic Packaging Tax: return and payment quarter-end 30 September 2025

If your business is liable for Plastic Packaging Tax (PPT), your return and payment covering the period 1 July to 30 September 2025 are due by 31 October 2025.

Who this applies to:

  • Businesses that manufacture or import 10 tonnes or more of finished plastic packaging components within a 12-month period.
  • Applies even if the packaging is empty or filled, and regardless of whether you’re a UK manufacturer or importer.

What’s required:

  • File a quarterly PPT return through your HMRC Business Tax Account.
  • Pay any tax due (standard rate applies to packaging with less than 30% recycled plastic).
  • Keep records to demonstrate recycled content, weight calculations, and exemptions.

Tips to stay compliant:

  • Track packaging data regularly. Don’t leave calculations until the end of the quarter spreadsheets or specialist software can help.
  • Check for exemptions. PPT does not apply to transport packaging used for imported goods or certain medical packaging.
  • Plan ahead for payment. Faster Payments usually clear same day, but Bacs can take up to three days.

Resource reminder:

  • HMRC provides detailed guidance on Plastic Packaging Tax returns and payments through its website.
  • If your business is below the 10-tonne threshold, you don’t need to pay, but you may still need to keep evidence of quantities for HMRC.

Penalty note:

  • Missing the deadline can trigger late submission penalties, late payment interest, and compliance checks.

31/10/25 – Corporation Tax returns: 31 October 2024 year ends

If your company’s financial year ended on 31 October 2024, you must file your Company Tax Return (CT600) with HMRC by 31 October 2025.

Who this applies to:

  • Limited companies with accounting periods ending 31 October 2024.
  • Even if your company made a loss or no tax is due, you still need to submit the return.

What’s required:

  • File your CT600 online through HMRC’s Corporation Tax service (or via MTD-compatible accounting software).
  • Include full statutory accounts, tax computations, and supporting schedules.
  • Ensure your accounts match what’s filed at Companies House, though the deadlines differ.

Tips to stay on top of it:

  • Don’t confuse filing and payment deadlines. Corporation Tax must usually be paid 9 months and 1 day after year end (so 1 August 2025 in this case), while the return filing deadline is 12 months after year end (31 October 2025).
  • Prepare early. Having your return filed before the payment deadline helps ensure accuracy.
  • Check attachments. Submissions often get rejected for missing iXBRL-tagged accounts or computations.

Resource reminder:

Penalty note:

  • Missing the filing deadline triggers an automatic £100 penalty, increasing the longer the return is late. Persistent late filers face higher fines and potential HMRC scrutiny.

31/10/25 – Self Assessment: 2024-25 paper tax returns

If you’re filing a paper Self-Assessment tax return for the 2024/25 tax year (covering income from 6 April 2024 to 5 April 2025), it must reach HMRC by 31 October 2025.

Who this applies to:

  • Individuals required to complete a Self-Assessment return who choose to file on paper rather than online.
  • This includes the self-employed, landlords, those with untaxed income, and individuals subject to the High-Income Child Benefit Charge.

What’s required:

  • Complete the SA100 paper return (and supplementary pages if relevant) and post it to HMRC by the deadline.
  • Ensure the return is fully signed, dated, and includes all supporting schedules.

Tips to avoid problems:

  • Allow postal time. HMRC must receive your paper return by 31 October, not just have it postmarked. Send it early.
  • Consider filing online. The online deadline is later 31 January 2026 and offers immediate confirmation of receipt.
  • Keep copies. Always keep a photocopy or digital scan of your return and proof of posting.

Resource reminder:

Penalty note:

  • Late paper returns (after 31 October) attract an automatic £100 fine, unless you file online by 31 January. Further penalties apply the longer it’s overdue.

Key Accounting Dates October 2025 Conclusion

Staying compliant with HMRC deadlines isn’t just about avoiding penalties it’s about keeping your business finances running smoothly. October has a particularly varied mix of obligations, so it pays to mark these dates in your diary and prepare well in advance.

If you’d like expert support in managing your accounting deadlines  from VAT and PAYE to Corporation Tax and Self Assessment – Accounting Wise is here to help. We’ll make sure you stay compliant, reduce admin stress, and have more time to focus on growing your business.

Need help with your Small Business accounts? Contact Accounting Wise today!

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