Filing to HMRC, Companies House, or both

Last updated: 9 August 2026

Short version. Answer the very first question in the wizard and you’re done deciding. “What are you filing?” offers your CT600 to HMRC, your accounts to Companies House, or both. Pick one and everything after it adapts. Nothing to untick later, and nothing to undo.

And if you change your mind halfway through, you don’t have to go back to the beginning. The final screen lets you add or remove either destination before you submit.

1. What gets filed where

A company’s annual filing has two separate destinations:

HMRC: your CT600 Corporation Tax Return (the CT600 XML plus the iXBRL accounts that support it).
Companies House: your Annual Accounts (iXBRL).

They’re two independent submissions to two different organisations, so they can be sent together or separately. SimpleCompanyTax asks which you want before you enter a single figure.

2. Choose when you start

“What are you filing?” is the first thing the wizard asks. Answer it and you’re done deciding. Whatever you pick shapes the rest of the run: the documents we prepare, the checks we make, and the credentials we ask for at the end.

The What are you filing? question at the start of the wizard, with three options: HMRC CT600 (Corporation Tax return only), Companies House (annual accounts only), and Companies House & HMRC CT600 (both). HMRC CT600 is selected. — The wizard’s first question. One click and the rest of the process follows.

Just the CT600 to HMRC

Pick HMRC CT600. That’s the whole answer. We prepare and send the Corporation Tax return only, and at the end you enter your UTR and Government Gateway details. Nothing goes to Companies House. This is the one to choose when your accounts are already filed.

Just the accounts to Companies House

Pick Companies House. We prepare and send the annual accounts only, and the single credential you need at the end is your 6-character authentication code. Most companies still owe HMRC a CT600 as well, so choose this when your CT600 is already filed or isn’t due yet.

Both, in one go

Pick Companies House & HMRC CT600, which is what most people need and what the wizard selects by default. One set of figures produces both filings and they go out together.

The underlying figures stay consistent whichever you choose. The documents prepared depend on the destination: HMRC receives the CT600, full accounts and tax computation, while Companies House receives the statutory accounts version intended for the public register. Choose both to prepare and send both sets together.

3. Changed your mind? You don’t have to start again

Your choice isn’t locked in. On the final Filing credentials screen, a Filing targets tick-box for each destination arrives pre-ticked to match what you picked at the start. Add one, remove one, and carry on. There’s no need to go back to the beginning of the wizard.

Filing credentials screen with Companies House and HMRC selected, including the accounts approval date and the credential fields for both destinations. — The final screen shows the selected filing targets, the approval date and only the credentials needed for those destinations.

Untick a destination and its credential fields disappear, and the submit button relabels itself so you can see exactly what’s about to be sent, whether that’s “Submit to HMRC”, “Submit to Companies House” or “Submit to HMRC & Companies House”. You just need to keep at least one ticked.

One exception. If you have told us your Corporation Tax period is different from your accounts period, because the company was dormant for part of the accounts period and started trading later, that filing goes to HMRC only and the Companies House box stays off. File the accounts to Companies House as their own filing. See dormant at first, then trading.

There’s a third route in too. If only one side is outstanding, your company page shows a “File CT600” or “File Accounts” action that opens the filing screen with the right target already selected.

4. Already filed one side? File just the other

A common case: “We’ve already filed our accounts to Companies House and just need to send the CT600 to HMRC. Is that possible?” Yes. You file only the outstanding side:

Accounts already done → file the CT600: choose HMRC CT600 at the first question. Nothing is sent to Companies House.
CT600 already done → file the accounts: choose Companies House. Nothing is sent to HMRC.

This works whether the other side was filed through SimpleCompanyTax or elsewhere (for example by your accountant). You’re simply not re-sending the part that’s already done. Your choice is remembered if you save and come back later.

5. Credentials you’ll need

You’re only asked for the credentials that match what you chose to file:

Companies House: your company’s 6-character authentication code.
HMRC: your 10-digit Corporation Tax UTR and the Government Gateway user ID and password for the account enrolled for the company’s Corporation Tax.

You also confirm the director approving the accounts and the accounts approval date. That date is not a password or filing credential. It is the date the directors approved the finished annual accounts, and it appears in both the draft and final accounts. See what to enter as the accounts approval date.

For where to find each of these (and how they’re handled), see “What credentials do I need to submit, and where can I find them?” in our FAQ.