I haven't had any activity at all — do I still file?

Yes. Every registered UK limited company files annual accounts, even one with literally zero activity. The dormant accounts template is specifically designed for exactly this case.

Can I file late?

You can, but penalties start accruing the day after the deadline. If you're already late, file as soon as possible to stop penalties from compounding.

Do I need to file a confirmation statement too?

Yes — but that's a separate Companies House filing (not covered by this product). Dormant accounts handle the accounts obligation; the confirmation statement (CS01) handles the company-details-up-to-date obligation.

What if my company had one tiny transaction?

Then you may not qualify as dormant. Read what counts as a dormant company before filing dormant accounts by mistake.