If you've incorporated after invoicing as a sole trader for a while, the good news is that most of what you already know still applies. A handful of specific details do change, and getting them right on your first few company invoices sets the right pattern going forward.
What stays exactly the same
The core legal requirements for a UK invoice - a unique sequential number, invoice date, clear description of goods or services, quantity, price, and total due - apply identically whether you trade as a sole trader or a limited company. VAT rules also work the same way regardless of your trading structure; registration depends on turnover, not on whether you have incorporated.
What actually changes
Your trading name becomes your registered company name (or a registered trading name) - not just whatever you called yourself as a sole trader
If you invoice under a name other than your exact registered company name, that registered name and company number must still appear on the invoice
Your company registration number should appear on your invoices and other business documents, even though it is not always a strict legal requirement on every invoice - it is standard good practice and some clients will ask for it
Your registered office address is a matter of public record via Companies House, which changes how much you may want to lean on a home address for invoicing purposes
If you have appointed yourself as an employee/director drawing a salary, that has payroll implications that are separate from invoicing itself, but often prompts a wider review of how money moves through the business
The mistake worth avoiding
The most common slip is simply forgetting to update the business details on invoices at all - sending company invoices that still show a sole trader's name, or that never got updated with the company number. It reads as inconsistent to clients, and it is an easy thing to overlook precisely because the invoice format otherwise feels unchanged.
Updating your business profile once - name, address, registration details - and having every invoice pull from that single source of truth avoids this entirely. That's exactly what Invoito's business profile settings are for: change it once, and it is correct on every invoice from that point on, without hunting down old template files to edit by hand.