Do I need to tell HMRC when I start trading?

Do You Need to Tell HMRC When You Start Trading?

Yes, you do need to inform HMRC when your business starts trading — and the timing matters. If you’ve incorporated a limited company, simply registering it with Companies House isn’t enough. You must also let HMRC know that you’re actively trading, especially if your company was previously dormant.

The key moment is when you add Corporation Tax services to your business tax account. This is where you officially notify HMRC of your company’s trading start date. Doing this triggers your company’s responsibility to file Corporation Tax returns and pay any tax due. If you delay, you risk penalties or interest on unpaid tax, even if your company hasn’t made a profit yet.

What adds complexity is the status of your company before this point. If your company was dormant — meaning it had no significant business activity — the rules change slightly depending on when you add Corporation Tax services. If you do it before your accounting reference date (usually the end of your first financial year), HMRC will expect your first return by the usual deadline: 12 months after the end of the accounting period.

But if you start trading after that date and only then notify HMRC, your accounting period may shift, and your deadlines could change. This can catch new business owners off guard.

Bottom line: Don’t assume HMRC knows you’re trading just because you’ve registered your company. You need to take action. As soon as you start earning income, making sales, or incurring expenses with the intent to trade, log in to your business tax account and add Corporation Tax services — and enter the correct start date. It’s a small step that keeps you compliant and avoids unnecessary stress down the line.