Your Autumn UK Compliance Checklist: Every Deadline Founders Need to Know

Summer winds down, and for a lot of founders, that’s when the “I’ll sort it later” pile finally catches up. If you run a UK company from abroad, autumn is exactly when HMRC and Companies House start expecting things from you — quietly, in the background, whether you’re paying attention or not.

The good news: none of this autumn UK compliance checklist is complicated once you know what’s coming. This guide walks through the real dates on the calendar this season, what each one actually means for you, and what happens if you miss it.

Why Autumn Matters More Than You’d Think

There’s no single “compliance season” in the UK the way there is in some countries — deadlines are spread across the year and tied to your own company’s dates. But autumn does carry a cluster of dates that apply broadly, plus it’s the natural runway into the busiest deadline of the year: the 31 January Self Assessment deadline.

Founders who use autumn to get organized walk into January calm. Founders who don’t tend to spend the last week of that month in a genuine scramble. This is the quieter option.

The Key Autumn Dates on Your Radar

5 October — Self Assessment Registration Deadline
If you started trading, became a company director, or began earning self-employed income at any point in the 2025/26 tax year and you haven’t registered for Self Assessment before, you need to notify HMRC by 5 October 2026. This isn’t your tax return itself — it’s just telling HMRC you exist and will need to file one.

This deadline applies if you’re self-employed earning over £1,000 a year, a company director, a landlord earning more than £2,500 in rental income, someone earning over £100,000, or if you have investment or untaxed foreign income. As a UK company director, this one is easy to overlook if your income mostly comes through PAYE — but it still applies.

If you miss it: you can still register late, but missing the deadline adds a failure-to-notify penalty on top of whatever late-filing penalty follows.

If you formed a new business partnership, or a new partner joined an existing one, during the 2025/26 tax year, that also needs to be reported to HMRC by 5 October.

Your Own Confirmation Statement and Annual Accounts Dates

Here’s the part that trips people up: Companies House deadlines aren’t fixed calendar dates for everyone — they’re based on your company’s own Accounting Reference Date (ARD), which by default is set as the last day of the month your company was incorporated. Your confirmation statement is due annually, and annual accounts are due 9 months after your accounting year end for a private limited company.

If your company was formed in an autumn month, this is very likely your season. Rather than guessing, check the date on your own Companies House record — it’s public and free to look up.

If you miss it: Companies House penalties escalate the longer accounts are late, and persistent non-filing can eventually lead to a formal strike-off notice against your company.

Corporation Tax — Check Your Own Accounting Period

Corporation Tax doesn’t follow the UK tax year — it follows your company’s accounting period. Payment is due 9 months and one day after your accounting period ends, and your CT600 return must be filed within 12 months of that same year end. So if your company’s financial year ended over the summer, your Corporation Tax payment deadline likely lands this autumn — well before the return itself is due.

This is the one founders most often get backwards: you have to estimate and pay what you owe before you’ve even filed the return, and late payment starts accruing interest from the day after the due date.

VAT Returns — Check Your Quarter

If you’re VAT-registered, your return and payment deadlines depend on your own VAT quarters, which don’t necessarily match the calendar quarter. Check your VAT registration certificate or your HMRC online account if you’re not sure when yours fall.

One thing worth knowing: HMRC’s penalty points system means each late VAT return earns a point, and once you hit the threshold — two points for annual filers, four for quarterly filers — a £200 fixed penalty applies to every late return after that.

Late October — Autumn Budget

The Autumn Budget is typically delivered in the second half of October, and it can bring changes to tax rates, funding schemes, or employer costs that affect your business going into the new year. Worth a calendar reminder even if nothing changes for you directly.

31 October — Paper Self Assessment Deadline

If you file a paper Self Assessment return rather than online, this year’s paper deadline is 31 October 2026. In practice, very few people still file this way — the online system is faster and gives you three extra months — but if paper is your process, don’t let this one slide past unnoticed.

Looking Ahead: 31 January

It’s not an autumn date, but it’s the reason autumn matters: your online Self Assessment return and any tax owed for 2025/26 are both due by 31 January 2027. Whatever you sort out or organize this autumn is time you don’t have to find in January.

Your Autumn Compliance Checklist

Use this list as a quick gut-check, not a full audit:

• • Confirm whether you needed to register for Self Assessment by 5 October

• • Look up your company’s actual Confirmation Statement and Annual Accounts due dates on Companies House

• • Check your Corporation Tax accounting period end date and when payment is due

• • Confirm your VAT quarter dates, if registered

• • Set a reminder for the Autumn Budget announcement

• • Start gathering documents for your January Self Assessment now, not in January

What to Do If You’re Already Behind

If you’re reading this and realizing you’ve missed something — you’re not the first founder this has happened to, and most of these situations are fixable. HMRC and Companies House both have processes for late filings, and the earlier you act, the less it tends to cost you in penalties and stress.

This is exactly the kind of thing our Compliance service exists for — we help founders track their actual dates, not generic ones, and handle the filings so nothing slips through while you’re focused on running your business.