Guides

File Company for Accountants

Updated 10 Jun 2026

File Company is a plain-English reference for UK company filing — written for owners, dated and sourced carefully enough to be useful to practitioners. If you spend time explaining the same filing mechanics to clients, these pages are built to be sent: every figure carries its effective date, the recent rule changes are flagged inline, and there's no fear-mongering for your clients to un-learn.

What's here that's worth sending

The client-explainer set — the pages that answer the questions clients actually ask:

• Company accounts and the CT600 — the two pillars, including the return-package point (CT600 + accounts + computations) and the first-year two-return mechanics
• CT600 deadlines — the pay-before-you-file order, stated plainly
• The confirmation statement and dormant companies — the admin filings clients forget
• Sole trader or limited company? — for the prospective-incorporation conversation

The current-rules set — where stale figures circulate widely:

• The 2025 size-threshold uplift (micro £1m / small £15m, FYs from 6 April 2025, with the look-back relief): micro-entity · small company
• The CT600 penalty uplift (£200/£400, filing dates from 1 April 2026 — the first rise since 1998): company tax return
• The April 2028 ECCTA package (software-only iXBRL filing, mandatory P&L, abridged removal) — note the date moved from 2027; material still citing 2027 is out of date
• MTD for Corporation Tax — scrapped, per the July 2025 Transformation Roadmap

Our approach to accuracy

Every figure on this site is drawn from a dated, GOV.UK-sourced internal reference and re-verified before publishing; effective dates are stated inline (penalties and thresholds especially, where the 2025–2026 changes made most circulating content wrong). If you spot something out of date, tell us — corrections are made quickly and credited where wanted.

Who's behind it

File Company is run by Carr Accounting Studio, a UK accounting practice. For referrals, white-label questions or anything else practice-to-practice: get in touch →