Small Business Tax Calendar: build a date system you can trust

Build the calendar from your actual obligations

Start with the business facts: sole trader, partnership or company; accounting period end; VAT registration and scheme; payroll status and pay dates; CIS or other relevant obligations; and whether Self Assessment payments on account apply. Then open the relevant HMRC account and notices. The calendar should point back to those records, not overwrite them with an internet checklist.

For every entry, record the period covered, return or report, payment, external deadline, internal preparation date, reconciliation date, evidence location, owner and backup owner. Add the transaction date on which cash must be cleared, not only the date you intend to press ‘pay’. This turns a deadline list into an operating control.

Use current HMRC anchors, then apply your own periods

HMRC’s Self Assessment guidance checked on 25 August 2026 states that, for the 2025/26 tax year, certain first-time or returning filers must notify HMRC by 5 October 2026; paper returns are due by 31 October 2026; online returns and payment are due by 31 January 2027; and a second payment-on-account date of 31 July applies where payments on account are required. Do not apply these dates to another tax year without checking the current HMRC page.

For companies, HMRC says the Company Tax Return deadline is 12 months after the end of the accounting period and Corporation Tax payment is usually due 9 months and one day after it. These are different dates. Your accounting period and any special circumstances determine the dates to enter. Company accounts and Companies House filing dates are separate controls that should also be added to the calendar.

Give VAT and payroll their own repeatable routines

HMRC says VAT Returns are usually quarterly and that online filing and payment are usually due one calendar month and seven days after the accounting period. It also says a registered business must submit a return even if there is no VAT to pay or reclaim, and should use its VAT online account to find the actual due date and payment-clearance information. Different VAT schemes can change the workflow, so do not use a standard date in place of your account record.

HMRC says employers that run payroll themselves report employee payments and deductions on or before payday and usually pay HMRC monthly, with a possible quarterly arrangement for certain small employers. Put pay dates, payroll cut-offs, report submission, HMRC payment and pension contributions in a single calendar view so an apparently successful pay run does not obscure the next cash commitment.

Separate sole-trader and company calendars

A sole trader’s calendar normally centres on the individual’s tax year, Self Assessment return and payments on account, together with VAT or payroll duties if they apply. Keep the business record of sales and costs aligned to the return period, but do not assume a sole trader has a Company Tax Return or a corporation-tax payment date.

A limited company needs a second calendar for its accounting period: Corporation Tax payment, Company Tax Return, annual accounts, confirmation statement, payroll and any director transactions. The director may also have a personal Self Assessment obligation. Give each entry an owner and entity label so a company deadline is not confused with the director’s personal deadline.

Add optional branches rather than blank rows for VAT, PAYE, CIS, pensions and international activity. When a business registers, changes scheme, hires or changes its accounting period, record the effective date and review which calendar branch has been activated.

Create preparation and reserve dates before the statutory date

Set an internal close date before every external deadline. For example, reconcile sales, purchases, payroll and bank records; identify missing invoices; review tax reserves; obtain approval; submit; then confirm that HMRC received the return or payment. Build the internal lead time around the quality of your records, the people available and the payment-clearing method rather than leaving each item to the deadline day.

Use a rolling cash forecast to ring-fence expected tax payments, but do not treat a reserve estimate as the final liability. Compare the forecast with completed returns, payroll reports, VAT account balances and adviser calculations as they become available. If the business may not be able to pay a tax liability when due, deal with the issue early through current HMRC channels and suitable qualified support rather than ignoring the calendar.

What to do, in order

1. 1

   List the tax and reporting obligations

   Identify structure, accounting period, VAT, payroll, Self Assessment and any other relevant duties before adding dates.

2. 2

   Source each date from HMRC records

   Use your accounts, notices, scheme information and current HMRC guidance; record where the date came from.

3. 3

   Add internal lead times

   Set close, reconciliation, review, approval and payment-clearance dates before the statutory deadline.

4. 4

   Link each entry to the cash forecast

   Reserve for expected payments and update the amount from reports and completed returns as evidence improves.

5. 5

   Review the calendar monthly

   Reconcile completed tasks, update changed dates and assign cover so deadlines do not depend on one person’s memory.