Company tax filing online
for just £20

The stress-free and straightforward way to submit returns to Companies House and HMRC in minutes
Company No.
8+ chars with 1 numeric & uppercase
HMRC Supervised Agent
& Recognised Provider
HM Revenue & Customs
How it works
Already trusted by thousands of UK businesses, our secure online software is designed for companies used to submitting returns through the HMRC website. It’s so intuitive that filing your accounts couldn’t be easier!
Step 1
Using our intuitive and easy to understand online portal, enter your financial details in the relevant fields.
Step 2
Review your filings using our online viewer. Once you are happy, add your Gateway Credentials and Authorisation Code.
Step 3
Submit and relax! Save and store your returns for your records. We'll send you digital receipts from HMRC and Companies House, where relevant.

Stress-free returns, straightforward price.

0asistax makes submitting your CT600 to HMRC and your accounts to Companies House so simple. And all for just £20.

Why choose 0asistax?

0asistax is designed specifically for small UK companies looking for a simpler, low-cost way to prepare and file corporation tax returns with confidence.

Simple user interface

So easy to use, you might wish you could file more often!

Built for small businesses

For businesses with simpler tax affairs, this is the place to file

One low price

Just £20 to submit to both HMRC and Companies House

Trusted software

Used by thousands of businesses to submit returns

Questions?
Feel free to browse our list of regularly asked queries, to help you along the way.
How much does it cost to submit to both HMRC and Companies House?

A submission fee of £20 applies per accounting period. This flat fee covers your filing regardless of whether you are submitting to Companies House, HMRC, or both - so there is no additional charge for dual submissions. This includes trading, dormant and property companies.

Can I file an amendment to HMRC or Companies House?

Yes, you can file an amended return if you need to make corrections after your original submission. In the Declaration page, please switch the amendment box to ‘Yes’ to confirm the submission includes amended figures.

Can I carry forward trading losses?

Yes, both trading losses and property losses can be carried forward within our template. If these losses are not surrendered - they are available to be offset against any future profits you make, either in the current period or in subsequent accounting periods, helping to reduce your overall tax liability over time.

Can I file for a company with property income?

Yes, property companies are supported on our platform. You can file as a property company provided your turnover does not exceed £5,200, making it well suited to smaller property businesses.

Can I claim Capital Allowances for my company?

Yes, we support Annual Investment Allowance (AIA) claims on qualifying asset purchases. This applies to cumulative purchases up to £1 million, allowing you to deduct the full cost of eligible assets against your taxable profits in the year of purchase.

Can I file dormant returns to Companies House and HMRC?

Yes, dormant company returns can be filed to HMRC and Companies House through our software. We support a full range of company types, including dormant, trading, and property companies, so you can manage all of your filing obligations in one place regardless of your company's activity status.

What credentials do I need to file to HMRC and Companies House?

To complete your submission, you will need the following credentials: your company's Unique Taxpayer Reference (UTR) number, along with your Government Gateway user ID and password. These are required to authenticate and submit your return to HMRC.

You will also need your Companies House authentication code to submit to Companies House. This refers to your company's authentication code - a 6-digit alphanumeric code (for example, ABC123) that is issued by Companies House upon incorporation.

How do I resolve a 1046 authentication error?

A 1046 error is an authentication failure that occurs when submitting a return to HMRC.

The most common causes of this are:

  1. Your Government Gateway user ID or password is incorrectly entered.
  2. The Corporation Tax service has not been activated on your Government Gateway account.
  3. An invalid UTR, or a problem with the HMRC Gateway itself.
  4. A previous accountant filed on your behalf using their own Agent Account, meaning the UTR may still be linked to their details.
Does this package include IXBRL tagged accounts?

Yes, all submissions are fully iXBRL compliant. Your CT600 return, statutory accounts, and Companies House submission are all automatically tagged in iXBRL format at the point of submission, in line with HMRC and Companies House requirements.

CT600 Filing Checklist (ensure you have completed everything you need)

Before submitting your CT600, please ensure the following has been completed:

  • All company details are accurate and up to date
  • The accounting period dates are correct
  • Income and expenditure figures match your financial records
  • A full balance sheet has been included
  • Ensure corporation tax service has been activated in the company’s Government Gateway account
  • Make sure you have all your credentials to hand