CT600 XML compliance
Full HMRC Corporation Tax schema v3. Every box validated against the LTS locally before we submit.
Corporation tax,
done right — from £10.
Production-ready CT600 returns and iXBRL statutory accounts for UK micro-entities and dormant companies. Built to HMRC and Companies House technical specifications, validated against the FRC taxonomy, and priced to replace your £400 accountant bill — £10/year if your company is dormant, £25/year if you're trading as a micro-entity.
- No card required to preview
- CT600 v3 schema compliant
- Own your data — download any time
The filing lifecycle
Five guided steps. Same day filing.
- 01
Connect
Look up your company on Companies House. We prefill everything — directors, SIC, registered office, accounting period.
- 02
Input
A short wizard asks for your balance sheet figures. Save, resume, amend — no forms printed, no emails lost.
- 03
Validate
We run the same HMRC Local Test Service and FRC Arelle validators used by accountants' software firms.
- 04
Review
See the CT600, the tax computation, and the statutory accounts side-by-side before anything is submitted.
- 05
File
Submit to HMRC via the Government Gateway, and file your accounts with Companies House — in one flow.
SCOPE
Focused scope. That's the feature.
Built for the 1M+ UK micro-entities that deserve affordable, accurate filings. Focused exclusively on single-entity UK companies for a more robust filing experience.
Designed for
- Dormant companies
- Single-director companies
- Low-turnover micro businesses
- Full 3-band CT with marginal relief
Not suitable for
- Associated companies
- R&D tax credit claims
- Group relief
- Overseas permanent establishments
PRICING
Two simple prices. No upsells.
Pay for exactly what you file: £10/year if your company is dormant, £25/year if you're trading as a micro-entity. Everything HMRC and Companies House require for your filing type is included.
Dormant filings
Dormant company
No trading activity during the period
£10 per company, per year
- Dormant Companies House accounts (iXBRL)
- Nil CT600 to HMRC
- Unlimited revision generations
- Downloadable XML + iXBRL files
Renews annually at £10 unless cancelled.
Most companies
Micro-entity
Trading company filing under FRS 105
£25 per company, per year
- Full FRS 105 statutory accounts (iXBRL)
- CT600 with complete tax computation
- Marginal relief + fiscal-year apportionment
- Unlimited revision generations
- Downloadable XML + iXBRL files
Renews annually at £25 unless cancelled.
Why pay £400+ to an accountant?
For simple dormant and micro-entity filings, you don't need to.
Traditional accountant
SimpleCompanyTax
Dormant filing
£150 – £400
£10
Trading micro-entity
£400 – £800
£25
Turnaround
2 – 4 weeks
Same day
Submission
Manual
Digital XML + iXBRL
Availability
Business hours
24/7 self-service
Amendments
Usually chargeable
Unlimited, free
For accountants & portfolio managers
Hundreds of micro-entities, one clean dashboard.
Whether you manage five dormant SPVs or five hundred, the firm console gives you filing status at a glance, bulk CSV ingestion for financial data, and a per-client audit trail you can hand to HMRC.
- Firm view — centralised status tracking across every engagement.
- Bulk imports — CSV trial balances, mapped once, reused forever.
- White-label exports — your letterhead on the PDF accounts.
- Role-based access — preparers, reviewers, clients, partners.
firm.simplecompanytax.co.uk
Company
Period
Status
Tax due
Acorn Studios Ltd
FY 2025
Filed
£9,159.90
Birchwood Ventures Ltd
FY 2025
Ready
£2,410.00
Copper & Rye Ltd
FY 2025
Validating
£14,820.00
Dormant Holdings I Ltd
FY 2025
Filed
£0.00
Evergreen Labs Ltd
FY 2025
Draft
—
Fernwell Consulting Ltd
FY 2025
Filed
£5,700.00
TECHNICAL CREDIBILITY
Compliance-first architecture.
Engineered to meet HMRC and Companies House technical specifications, with separate, reliable submission logic for each.
iXBRL statutory accounts
FRC-tagged accounts ready for both Companies House and HMRC. No manual tagging.
FRS 105
The UK micro-entity reporting standard, tagged against the current FRC taxonomy so your accounts are HMRC and Companies House-ready with no manual iXBRL work.
Direct Gateway integration
Government Gateway submission protocol. IRmark receipt returned on every successful file.
Marginal relief, automated
Full three-band corporation tax computation with marginal relief where applicable.
Own your data
Download CT600 XML, iXBRL accounts, and computations at any time. No vendor lock-in.
Data integrity & security
Treated like a bank would treat it.
- Enterprise-grade AES-256 encryption, at rest and in transit.
- No third-party data selling or sharing — ever.
- Full file portability — download your XML, iXBRL, PDFs at any time.
- Government Gateway preparation with IRmark verification.
- Row-level security on every record, service-role writes only.
Our goal is to give UK micro-entities the same filing accuracy that a FTSE 100 gets — at a fraction of the cost, and without the friction.
The SimpleCompanyTax teamUK tax software engineers
ANSWERS
Questions directors actually ask.
Do I need an accountant?
Not if your company is a simple micro-entity. SimpleCompanyTax handles the entire CT600 + iXBRL flow in plain English. For complex group structures, R&D claims, or associated companies, an accountant is still the right answer. Read more →
What is a CT600?
The CT600 is HMRC's electronic corporation tax return, filed in XML and accompanied by iXBRL-tagged accounts. Full guide →
Is my company a micro-entity?
Most single-director UK limited companies are. The thresholds are turnover under £632,000, balance sheet under £316,000, and under 10 employees. Check eligibility →
What if my company is dormant?
Dormant companies still have to file. We handle dormant accounts at Companies House plus a nil CT600 to HMRC if needed. Dormant company guide →
How does SimpleCompanyTax submit my filings?
Two separate submission paths. CT600 returns go to HMRC via the Government Gateway Transaction Engine; statutory accounts go to Companies House via their CH API. Every submission returns an IRmark receipt that we store against your filing record. You can still preview and download everything before submitting — no card is required to get to that point.
Can I cancel anytime?
Yes. Your subscription renews annually at the plan price you chose (£10 dormant or £25 micro-entity) and you can cancel any time from your account.
Ready to file your corporation tax?
From £10 per company, per year. CT600, iXBRL, and Companies House submission — in one flow.