14 October 2026: CT61 deadline
A CT61 is used by companies that deduct Income Tax from certain payments, such as some payments of yearly interest, royalties and other qualifying payments.
Where a CT61 return is required for the quarter ending 30 September 2026, the associated return and tax are normally due within 14 days of the end of the return period, making 14 October 2026 the relevant deadline.
CT61 does not apply to every limited company. If you are unsure whether payments made by your company require tax to be deducted, it is worth checking before assuming that no return is required.
HMRC provides further information here: Corporation Tax CT61 guidance on GOV.UK.
19 October 2026: PAYE, NIC and CIS postal payment deadline
Employers paying HMRC by post generally need their PAYE payment to reach HMRC by the 19th of the month.
For October 2026, this covers PAYE and National Insurance liabilities for the tax month ending 5 October 2026. The same date is relevant for quarterly PAYE payers whose quarter ended on 5 October.
PAYE bills can include more than just employee Income Tax. Depending on the employer, the amount payable can include:
- Income Tax deducted through PAYE;
- employee and employer National Insurance contributions;
- student and postgraduate loan deductions;
- Construction Industry Scheme deductions; and
- Apprenticeship Levy liabilities where applicable.
Most businesses now pay electronically, in which case the later 22 October deadline normally applies.
19 October 2026: CIS monthly return
If you operate as a contractor under the Construction Industry Scheme (CIS), your return covering payments to subcontractors during the tax month ending 5 October 2026 is due by 19 October 2026.
CIS returns report payments made to subcontractors and the deductions taken from those payments.
Late CIS returns can result in automatic penalties. HMRC’s standard penalty starts at £100 when a return is one day late and increases if the return remains outstanding.
Contractors can find the current filing rules here: File your CIS monthly returns on GOV.UK.
19 and 22 October 2026: PAYE Settlement Agreement payments
October also contains an important deadline for employers that have a PAYE Settlement Agreement (PSA).
A PSA allows an employer to make one annual payment covering the tax and National Insurance due on certain minor, irregular or impracticable employee expenses and benefits.
For benefits and expenses covered by a PSA for the 2025/26 tax year, payment is due by:
- 19 October 2026 if paying by post; or
- 22 October 2026 if paying electronically.
The payment includes the Income Tax and Class 1B National Insurance due under the agreement.
Further information is available from HMRC: PAYE Settlement Agreement deadlines on GOV.UK.
22 October 2026: Electronic PAYE, NIC and CIS payments
For most employers paying electronically, 22 October 2026 is the deadline for the PAYE and National Insurance payment relating to the tax month ending 5 October.
The same deadline applies to quarterly PAYE payers for the quarter ending 5 October 2026.
Do not leave the payment until the last minute if your chosen payment method takes several working days to clear. HMRC considers when the money reaches its account, not simply when you instruct your bank to make the payment.
You can check payment methods and processing times here: Pay employers’ PAYE on GOV.UK.
30 October 2026: Non-Resident Landlord Scheme
Under the Non-Resident Landlord Scheme (NRLS), letting agents and certain tenants may have to deduct tax from rental income paid to a landlord whose usual place of abode is outside the UK.
Where tax is due for the quarter ending 30 September 2026, the quarterly return and payment are due no later than 30 October 2026.
The rules can differ where HMRC has authorised a non-resident landlord to receive their rent without tax being deducted, so landlords, agents and tenants should check which arrangements apply.
HMRC explains the quarterly reporting process here: Non-Resident Landlord Scheme quarterly returns on GOV.UK.
30 October 2026: Plastic Packaging Tax return and payment
Businesses registered for Plastic Packaging Tax have another deadline towards the end of October.
The return covering the accounting period from 1 July to 30 September 2026 must be submitted and any tax paid by the last working day of the following month.
Because 31 October 2026 falls on a Saturday, the relevant deadline is Friday 30 October 2026.
Plastic Packaging Tax generally affects businesses that manufacture or import sufficient quantities of finished plastic packaging components. Registered businesses also need to maintain records supporting the figures reported on their quarterly returns.
See HMRC’s guidance for the latest requirements: Submit your Plastic Packaging Tax return on GOV.UK.
31 October 2026: Company Tax Return deadline
Companies with a Corporation Tax accounting period ending 31 October 2025 will normally have until 31 October 2026 to submit their Company Tax Return to HMRC.
A Company Tax Return is normally due 12 months after the end of the accounting period.
Do not confuse this with the Corporation Tax payment deadline. For most companies, Corporation Tax itself is payable earlier, usually nine months and one day after the end of the accounting period.
A Company Tax Return normally includes the company’s Corporation Tax calculation together with the relevant accounts and supporting information.
HMRC’s Company Tax Return guidance is available here: Company Tax Returns on GOV.UK.
31 October 2026: Paper Self Assessment deadline
If you are submitting a paper Self Assessment tax return for the 2025/26 tax year, HMRC must normally receive it by 31 October 2026.
This is much earlier than the online filing deadline of 31 January 2027.
If you miss the paper deadline, you can normally avoid filing late by submitting your return online instead, provided you are eligible to file online and do so by the January deadline.
Do not confuse the filing deadline with the tax payment deadline. Tax due through Self Assessment for 2025/26 is generally payable by 31 January 2027, along with the first payment on account for 2026/27 where applicable.
You can check the official deadlines here: Self Assessment tax return deadlines on GOV.UK.
What happens if you miss an HMRC deadline?
The consequences depend on the tax involved and whether you have missed a filing deadline, payment deadline or both.
You could face:
- automatic late filing penalties;
- late payment penalties;
- interest on unpaid tax;
- additional penalties where a return remains outstanding for a prolonged period; and
- extra HMRC correspondence and potential compliance action.
Some penalty regimes, including VAT, use a points-based system for late submissions, while other taxes have their own penalty structures.
If you realise that you have missed a deadline, dealing with it quickly is usually the best approach. Submit any outstanding return, establish how much is owed and arrange payment as soon as possible.
Preparing for Self Assessment season
October is also a good point in the year to get ahead of the January Self Assessment rush.
If you need to file a 2025/26 return, start gathering:
- sales and self-employed income records;
- business expense receipts and invoices;
- bank and savings interest statements;
- dividend information;
- property income and expense records;
- pension contribution details;
- capital gains information; and
- details of any payments on account already made.
Submitting your return before January does not normally mean you have to pay your tax early. It simply gives you more time to understand the amount due and plan your cash flow before the payment deadline.
Practical tips for staying on top of October’s accounting deadlines
A few simple processes can prevent tax deadlines becoming a last-minute problem:
- Keep your bookkeeping up to date. Monthly bookkeeping makes VAT, payroll and year-end work much easier.
- Check your HMRC account regularly. Do not rely solely on reminder letters or emails.
- Allow time for payments to clear. Different HMRC payment methods have different processing times.
- Keep business and personal transactions separate. A dedicated business bank account can make record keeping considerably simpler.
- Send information to your accountant early. Waiting until the deadline leaves less time to identify missing records or unexpected tax liabilities.
- Plan for upcoming tax bills. Knowing what is due several months in advance can make a significant difference to cash flow.
Accounting Wise tip: A tax deadline should ideally be the final date for completing the process, not the date you start thinking about it. Keeping your records current throughout the year gives you more time to deal with problems and plan for upcoming payments.
Keep on top of your October 2026 accounting dates
October contains several important UK tax deadlines, particularly for Self Assessment registration, payroll, CIS, VAT and companies with relevant Corporation Tax accounting periods.
The key dates to watch are 1, 5, 7, 14, 19, 22, 30 and 31 October 2026, but not every deadline will apply to every business.
Keeping accurate records, checking your HMRC accounts and dealing with returns well before their final filing dates can reduce the risk of penalties and give you a much clearer picture of your upcoming tax liabilities.
If you would rather spend your time running your business than keeping track of HMRC deadlines, Accounting Wise can help. From bookkeeping and VAT to payroll, Self Assessment and limited company accounts, we can help keep your accounts organised and your tax obligations on track.
