Tax Diary December 2026 and January 2027: Key UK Tax Deadlines

The Tax Diary December 2026 and January 2027 covers important UK tax deadlines for businesses, company directors, employers, contractors, landlords and individuals completing Self Assessment.

December includes Corporation Tax, VAT, PAYE, CIS and Companies House deadlines. January is particularly important because it includes the 31 January Self Assessment filing and payment deadline, alongside Corporation Tax, VAT and payroll obligations.

This UK Tax Diary 2026-27 explains the main dates, who they affect and what taxpayers should prepare before each deadline.

The dates are general guidance. Some deadlines depend on an individual company’s accounting period, the VAT scheme used, payment method or specific HMRC arrangements.

UK Tax Diary 2026-27: December and January Deadlines at a Glance

December 2026 Tax Deadlines

December can be a challenging month for businesses managing tax obligations alongside Christmas holidays, reduced working days and year-end accounting activities. Businesses unfamiliar with VAT reporting may find it useful to review a comprehensive guide to UK VAT before preparing their December and January filing obligations.

The following dates should be included in your UK tax deadline checklist.

1 December 2026: Corporation Tax Payment Deadline

Corporation Tax is normally payable on 1 December 2026 for companies whose accounting period ended on 28 February 2026, unless they are required to pay by quarterly instalments.

Most companies must pay Corporation Tax within nine months and one day of their accounting period ending.

However, paying Corporation Tax and submitting the Company Tax Return are separate obligations.

Businesses should check their Corporation Tax calculations, confirm the correct payment reference and arrange payment before the deadline. Companies that need help calculating their liability, checking payment deadlines or preparing tax computations can benefit from professional Corporation Tax services in London.

7 December 2026: VAT Return and Payment Deadline

VAT returns and payments are normally due on 7 December 2026 for VAT accounting periods ending 31 October 2026.

The standard VAT deadline is generally one calendar month and seven days after the end of the accounting period.

Different rules may apply to businesses using alternative VAT arrangements, including the Annual Accounting Scheme.

Before submission, businesses should review:

• Sales and purchase invoices
• Input and output VAT calculations
• VAT adjustments
• Reverse charge transactions
• Import VAT
• Credit notes
• Bank and VAT reconciliations

Businesses operating under Making Tax Digital for VAT should also ensure their digital records and reporting software meet HMRC requirements. Where reverse charge transactions appear in the accounting records, businesses should understand how the VAT reverse charge works before completing their VAT calculations.

19 December 2026: PAYE and National Insurance Postal Payment

PAYE and National Insurance deductions for the tax month ending 5 December 2026 are normally due by 19 December 2026 when payment is made by cheque through the post.

However, 19 December 2026 falls on a Saturday.

Employers paying by post should therefore ensure HMRC receives their payment by Friday 18 December 2026.

PAYE liabilities may include:

• Employee Income Tax deductions
• Employee National Insurance contributions
• Employer National Insurance contributions
• Student loan deductions
• Apprenticeship Levy where applicable
• CIS deductions

Employers using electronic payments normally have until 22 December 2026.

19 December 2026: CIS300 Monthly Return Deadline

Contractors operating under the Construction Industry Scheme must normally submit their CIS300 monthly return for the tax month ending 5 December 2026 by 19 December 2026.

The monthly return reports payments to subcontractors and any CIS deductions made.

Contractors should review subcontractor verification details, payments, materials costs and deduction rates before filing.

Although the deadline falls on a Saturday, the normal filing obligation still applies. Submitting earlier can help avoid unexpected software or processing issues. Construction contractors managing subcontractor verification, deduction calculations and monthly submissions can seek specialist CIS accounting services in London to support accurate reporting.

19 December 2026: CIS Tax Payment by Post

CIS tax deducted from subcontractor payments for the month ending 5 December 2026 must normally reach HMRC by 19 December 2026 when payment is made by post.

Because this falls on a Saturday, postal payments should reach HMRC by Friday 18 December 2026.

For electronic payments, the normal deadline is 22 December 2026.

22 December 2026: Electronic PAYE and CIS Payment Deadline

Electronic PAYE, National Insurance, student loan and CIS payments for the tax month ending 5 December 2026 are normally due by 22 December 2026.

This deadline falls shortly before Christmas, so businesses should check their payment method and processing times.

Employers should ensure their payroll records, deductions and HMRC payment references are accurate before submitting payment.

30 December 2026: Self Assessment Tax Through Your PAYE Code

The 30 December 2026 deadline is particularly important for certain individuals who complete Self Assessment but also pay tax through PAYE.

Eligible taxpayers can have a Self Assessment liability of less than £3,000 collected through their PAYE tax code if they submit their 2025/26 online tax return by 30 December 2026.

The conditions generally include:

• Owing less than £3,000 in Self Assessment tax
• Already paying tax through PAYE
• Submitting the online return by 30 December
• Having sufficient PAYE income for HMRC to collect the liability

HMRC may refuse tax-code collection if the deductions would exceed its permitted limits.

This deadline is different from the general online Self Assessment filing deadline of 31 January 2027.

Taxpayers who want to use this payment option should therefore prepare and submit their returns before the December deadline. Taxpayers considering collection through their PAYE code should also understand the wider HMRC Self Assessment requirements, including eligibility, reporting obligations and payment arrangements.

31 December 2026: Corporation Tax Return Deadline

Companies with an accounting period ending 31 December 2025 must normally submit their Company Tax Return to HMRC by 31 December 2026.

A Company Tax Return is generally due within 12 months of the end of the accounting period.

Companies should check that their statutory accounts, Corporation Tax computations and relevant disclosures are consistent.

Late filing penalties can apply even when the company has already paid its Corporation Tax.

31 December 2026: Companies House Accounts Deadline

Private companies with an accounting period ending 31 March 2026 will normally need to file annual accounts with Companies House by 31 December 2026.

Private limited companies generally have nine months after their financial year-end to submit annual accounts.

However, different deadlines may apply to:

• First company accounts
• Shortened accounting periods
• Extended accounting periods
• Changes to the accounting reference date

Companies should confirm their individual filing deadline rather than relying solely on a standard tax diary.

Tax Diary January 2027: Important HMRC Deadlines

January is one of the most important months in the income tax diary, particularly for individuals within Self Assessment.

The 31 January 2027 deadline covers online Self Assessment returns for 2025/26, outstanding tax liabilities and the first payment on account for 2026/27 where applicable.

Companies, employers and contractors also have several important filing and payment obligations during January.

1 January 2027: Corporation Tax Payment Deadline

Corporation Tax is normally due on 1 January 2027 for companies whose accounting period ended 31 March 2026, unless quarterly instalment rules apply.

However, 1 January 2027 is a bank holiday.

Companies using payment methods that require working-day processing should arrange payment so that HMRC receives cleared funds by the previous working day, normally 31 December 2026.

HMRC accepts certain Faster Payments and card payments on weekends or bank holidays, but businesses must check the processing rules for their payment method.

Companies should not assume that the bank holiday automatically extends the Corporation Tax deadline.

7 January 2027: VAT Return and Payment Deadline

VAT returns and payments are normally due on 7 January 2027 for accounting periods ending 30 November 2026.

Businesses should verify the deadline through their VAT online account, as alternative arrangements may apply.

January VAT preparation should include reviewing transactions processed during the Christmas period, including:

• Customer refunds
• Credit notes
• Year-end adjustments
• Supplier invoices
• Import and export transactions
• VAT corrections

VAT-registered businesses should ensure the return is submitted and payment reaches HMRC by the applicable deadline. Businesses preparing their January VAT submissions can use professional VAT services in London to review transactions, identify reporting errors and meet HMRC filing requirements.

14 January 2027: CT61 Return and Payment Deadline

The 14 January 2027 deadline applies to companies required to submit a CT61 return and pay Income Tax deducted from relevant payments for the quarter ending 31 December 2026.

A CT61 return may be required where a company makes certain payments after deducting Income Tax.

Examples can include:

• Certain interest payments
• Annual payments
• Royalties
• Other relevant payments subject to Income Tax deduction

Not every company needs to submit a CT61 return.

For example, a company paying interest on certain loans from directors may need to consider whether Income Tax must be deducted and reported.

Where CT61 applies, companies should calculate deductions accurately and submit the return and corresponding payment by the deadline.

19 January 2027: PAYE and National Insurance Postal Payment

PAYE and National Insurance deductions for the tax month ending 5 January 2027 must normally reach HMRC by 19 January 2027 where payment is made by cheque through the post.

Employers paying electronically normally have until 22 January 2027.

Payroll records should be reconciled before payment, particularly where December payroll included early salary payments, bonuses or other adjustments. Employers managing monthly payroll liabilities may benefit from professional PAYE services in London to calculate deductions, reconcile payroll records and maintain accurate HMRC payments.

19 January 2027: CIS300 Monthly Return Deadline

The CIS300 monthly return for the tax month ending 5 January 2027 must normally be submitted by 19 January 2027.

Contractors should report subcontractor payments and deductions accurately, including any payments made during the Christmas and New Year period.

Keeping subcontractor records up to date can help reduce late filing risks. Businesses operating in construction should also understand the CIS rules for contractors, particularly how subcontractor payments, deduction rates and monthly reporting requirements apply.

19 January 2027: CIS Tax Payment by Post

CIS tax deducted for the month ending 5 January 2027 must normally reach HMRC by 19 January 2027 when payment is made by post.

For electronic payments, the normal deadline is 22 January 2027.

Contractors should ensure the amount paid agrees with the CIS deductions recorded in their monthly returns.

22 January 2027: Electronic PAYE and CIS Payment Deadline

Electronic payments of PAYE, National Insurance contributions, student loan deductions and CIS deductions for the tax month ending 5 January 2027 are normally due by 22 January 2027.

Employers should allow sufficient processing time and confirm that HMRC receives the correct payment reference.

Businesses operating quarterly PAYE payment arrangements should also check whether their quarterly liability is due on this date.

31 January 2027: Online Self Assessment Tax Return Deadline

The most important date in the Tax Diary January 2027 is 31 January 2027.

This is the normal deadline for submitting online Self Assessment tax returns for the tax year ending 5 April 2026.

The deadline can affect:

• Self-employed individuals
• Sole traders
• Landlords
• Company directors who are required to file
• Individuals receiving untaxed income
• Individuals with relevant capital gains
• Other taxpayers required by HMRC to complete Self Assessment

Although 31 January 2027 falls on a Sunday, the online filing deadline remains 11:59pm on 31 January 2027.

Taxpayers should not assume that the deadline automatically moves to Monday. Individuals who need help organising income records, checking allowable expenses or submitting their return can use professional Self Assessment tax return services in London.

What happens if you miss the Self Assessment deadline?

Late filing can result in an initial £100 penalty, even if there is no tax to pay, unless an exception applies.

Additional penalties may arise where the return remains outstanding for longer periods.

Taxpayers should therefore submit their returns early enough to resolve any missing information or technical issues.

31 January 2027: Self Assessment Income Tax Payment Deadline

The same date is also the normal payment deadline for outstanding Self Assessment liabilities relating to 2025/26.

This can include:

• Outstanding Income Tax
• Class 4 National Insurance contributions where applicable
• Other liabilities included in the Self Assessment calculation
• The first payment on account for 2026/27, where required

Taxpayers should remember that filing a return and paying the tax are separate obligations.

Submitting a return on time does not remove the requirement to pay the liability by the deadline.

First payment on account for 2026/27

Some Self Assessment taxpayers must make advance payments towards the following tax year’s liability.

Where payments on account apply, the first payment for 2026/27 is normally due by 31 January 2027.

The second payment is normally due by 31 July 2027.

Taxpayers whose income has reduced may be able to claim a reduction in their payments on account, but the estimate should be reasonable to avoid unnecessary interest.

31 January 2027: Corporation Tax Return Deadline

Companies with an accounting period ending 31 January 2026 must normally submit their Company Tax Return by 31 January 2027.

The standard filing deadline is 12 months after the end of the accounting period.

Because 31 January 2027 falls on a Sunday, companies should prepare their accounts and tax computations early rather than relying on last-minute filing.

A Company Tax Return may still be required even where the company has made a loss or has no Corporation Tax to pay.

31 January 2027: Companies House Accounts Deadline

Private companies with an accounting period ending 30 April 2026 will normally need to file their annual accounts with Companies House by 31 January 2027.

As this deadline falls on a Sunday, companies should avoid assuming they can automatically file on the following working day.

The actual filing deadline should be checked through the company’s Companies House record.

Other UK Tax Deadlines to Remember

Some tax and company filing obligations depend on a transaction date, payroll date or individual company review period rather than a fixed monthly deadline.

Capital Gains Tax on UK Residential Property

Capital Gains Tax arising on most taxable disposals of UK residential property must normally be reported and paid within 60 days of completion.

This is particularly relevant for landlords, property investors and individuals disposing of residential property where a taxable gain arises.

The exact deadline depends on the completion date.

Non-UK residents can also have reporting obligations when disposing of UK property, including circumstances where no tax is payable.

PAYE Full Payment Submission Deadlines

Employers must normally submit a Full Payment Submission (FPS) to HMRC on or before employees are paid.

An FPS reports payroll information, including pay, Income Tax and National Insurance deductions.

Employers paying staff earlier than usual because of Christmas or New Year should be aware of HMRC’s special reporting arrangements.

Where an employee receives their salary early because of a holiday, employers should generally report the normal contractual payday on the FPS and submit the FPS on or before that normal payday.

This can help prevent problems with employees’ benefit calculations, including Universal Credit.

Companies House Confirmation Statement Deadlines

Companies House confirmation statements generally need to be filed within 14 days of the end of the company’s review period.

Unlike annual accounts, the confirmation statement deadline is based on the individual company’s review period.

Companies should check their specific confirmation statement date and keep company information up to date.

Making Tax Digital for Income Tax: 7 February 2027 Deadline

Businesses and individuals within Making Tax Digital for Income Tax should also prepare for the next quarterly update deadline.

The third quarterly update for the 2026/27 tax year is due by 7 February 2027.

For taxpayers using standard tax-year reporting periods, the update covers the period from 6 April 2026 to 5 January 2027.

For taxpayers using calendar-quarter reporting periods, it normally covers 1 April 2026 to 31 December 2026.

Both arrangements have the same 7 February 2027 submission deadline.

Affected individuals should maintain their digital records and ensure their MTD-compatible software is ready.

Corporation Tax Payment and Filing Deadlines Are Different

One common source of confusion is the difference between paying Corporation Tax and submitting the Company Tax Return.

For most companies:

Larger companies may need to pay Corporation Tax through quarterly instalments. Businesses should therefore maintain separate reminders for Corporation Tax payments, Company Tax Returns and Companies House accounts. Company directors should understand how Corporation Tax works, including the distinction between calculating the liability, paying the tax and filing a Company Tax Return.

How to Prepare for December and January Tax Deadlines

The end of December and January can be particularly demanding because several filing and payment obligations overlap.

A structured approach can help businesses maintain compliance.

Review outstanding tax liabilities

Identify any Corporation Tax, VAT, PAYE, CIS or Self Assessment amounts that need to be paid.

Prepare Self Assessment returns early

Individuals should gather employment information, business income records, rental income details, relevant expenses and other taxable income information before the January deadline.

Check VAT and payroll records

Reconcile VAT returns and payroll liabilities before submission to reduce errors and last-minute corrections. Businesses using compatible software should also review whether they need Making Tax Digital VAT support in London to maintain digital records, reconcile transactions and submit returns correctly.

Allow for Christmas and New Year bank holidays

Payments requiring bank processing should be arranged in advance, particularly around 19 December, 1 January and 31 January.

Check company filing deadlines

Review Corporation Tax return deadlines, Companies House accounts dates and confirmation statement obligations separately.

Prepare for MTD quarterly reporting

Individuals within MTD for Income Tax should maintain digital records ahead of the 7 February 2027 quarterly update deadline.

Common Tax Deadline Mistakes to Avoid

• Confusing Self Assessment filing and payment: Both can be due on 31 January, but they are separate obligations.
• Missing the 30 December deadline: Taxpayers wanting eligible tax liabilities collected through PAYE must submit their return earlier than the normal online deadline.
• Assuming bank holidays extend payment deadlines: HMRC may require payments to reach it before a holiday, depending on the payment method.
• Forgetting the CT61 deadline: Companies making relevant payments subject to Income Tax deductions may have an additional quarterly reporting obligation.
• Ignoring Companies House filing dates: The accounts deadline is separate from the Corporation Tax return deadline.
• Leaving digital tax records incomplete: Taxpayers within MTD for Income Tax must prepare quarterly updates using compatible software.

CASE STUDY: Helping a Business Prepare for December and January Tax Deadlines

A growing business contacted our Fulham office after realising that several tax and filing obligations were falling close together over December and January.

The company needed to manage VAT, PAYE, National Insurance and Corporation Tax, while the director also had a personal Self Assessment return due by 31 January 2027.

CIGMA Accounting reviewed the company’s accounting period, VAT cycle, payroll liabilities, Companies House filing dates and the director’s personal tax position. We separated each obligation so that Corporation Tax payments, Company Tax Returns, annual accounts and Self Assessment were not treated as one combined deadline.

Particular attention was given to dates affected by Christmas and New Year. Because some payment deadlines fell close to weekends or bank holidays, we helped the business plan payment timing in advance rather than assuming the deadline would automatically move to the next working day.

We also reviewed whether the director could use the 30 December 2026 Self Assessment tax-code collection option for an eligible liability below £3,000, and ensured the wider January cash-flow forecast included any payment on account due.

A forward-looking tax calendar was then created covering December, January and the next MTD quarterly deadline in February.

The client left with a clearer understanding of their position, options, and next steps.