We Prepare the Corporation Tax Return UK Practices Put Their Name To.
Corporate tax services UK accountancy firms use as an extension of their own tax team. Accurate CT600 preparation and HMRC filing support delivered in 5 working days, reviewer ready, senior CA reviewed, and packaged for clean sign off at a fraction of the cost.
Built for UK Tax Practices of Every Size.
Whether you face a growing CT backlog, need cover during filing peaks, or want to free up senior staff for advisory work, our corporate tax outsourcing service slots directly into your workflow.
Solo and Small Practices
Peak season cover without hiring a UK tax consultant you only need for four months of the year.
- Affordable per return pricing, no retainer
- No minimum volume commitment
- Same 5 day turnaround from day one
- Works inside your existing tax software
Growing Tax Practices
- Scale capacity instantly at filing peaks
- No permanent headcount required
- Dedicated account contact for your firm
- Senior CA reviewed output on every file
Mid Size and Multi Office Groups
- High volume CT capacity on demand
- Group relief and consolidation support
- Monthly volume reporting and SLA tracking
- Merged R&D, ERIS, and marginal relief handled
Everything Covered,
Computation to Filing.
From raw accounts to iXBRL tagged CT600 return. Our corporation tax return UK service handles every stage of preparation so your team focuses on client relationships and sign off.
CT600 Return Preparation
- CT600 corporation tax return preparation
- Tax computation schedules with full workings
- Capital allowances (AIA, FYA, WDA) schedules
- Deferred tax calculations and disclosures
Reliefs and Claims
- R&D tax credit computation and supporting notes
- Loss relief claims and surrender schedules
- Group relief allocations and surrenders
- Associated company rules and marginal relief
Compliance and Filing
- HMRC electronic filing support and iXBRL tagging
- Interest and penalties exposure summary
- Prior year adjustment and error correction notes
- Instalment payment computation for large companies
Reviewer Ready Delivery
- Open point query log with variance explanations
- Reviewer handover pack with sign off checklist
- Version controlled file delivery
- Revisions and amendments included at no extra cost
Your clients' software.
Our team knows it.
No onboarding friction. No tool switching. Our corporate tax services UK specialists step straight into the software your practice already runs on and get to work from day one.
Talk to our team
Don't see your software? We adapt to your needs. Since HMRC closed its free joint filing service on 31 March 2026, every online tax return UK companies submit has to run through commercial software anyway.
Corporate Tax Outsourcing: But Why?
Because your senior team's time is worth more than corporation tax preparation. Here's exactly what corporate tax outsourcing gives a UK practice back.
Save Up to 50% in Costs
Replace expensive internal tax preparation time with expert offshore support. Pay per return, not per headcount.
Scale at Peak Season Instantly
Add CT preparation resource during your April to June and October to December filing peaks without any permanent commitment.
Senior CA Reviewed Every File
Every CT600 is quality checked by a qualified CA before delivery. You receive reviewer ready output, not a draft that needs fixing.
No Software Migration
We work directly inside TaxCalc, IRIS Tax, CCH, or Alphatax from day one. Your workflow and templates stay exactly as they are.
GDPR Secure from Day One
NDA and DPA signed before work begins. Encrypted file transfer, role based access, and full GDPR compliance throughout.
Six Reasons UK Firms Choose Us for Corporate Tax Outsourcing.
Expert reviewed CT600 returns, guaranteed turnaround and seamless software compatibility — the corporate tax services UK practices stay with, from a partner built specifically for UK accounting and tax firms.
Up to 50% cost saving
Reduce corporation tax preparation costs compared to internal staff time, without sacrificing review quality or accuracy.
5 day turnaround
Consistent delivery in 5 working days from receipt of signed accounts and trial balance, even at peak filing season.
HMRC compliant returns
All CT600 returns prepared in line with current HMRC requirements. R&D, marginal relief, and group relief scenarios handled correctly.
Senior CA reviewed output
Every CT file is quality checked by a qualified CA before delivery. No unreviewed work leaves our team.
Scalable peak capacity
Add tax preparation resource instantly during the spring and autumn filing peaks. Scale back when pressure eases.
GDPR secure delivery
NDA signed before work begins. Encrypted file transfer, role based access controls, and full GDPR compliance throughout.
How Our Corporation Tax Return UK Service Works
Five steps from signed accounts to filed return, with your reviewer in control at every handover point. It is the same corporation tax return UK workflow your own team already follows, staffed by ours.
Share Signed Accounts
Secure upload of signed accounts and supporting schedules
CT600 Prepared
Computation and return prepared by CT specialists
Senior CA Review
Reviewed by an experienced senior CA
Quality Check
Multi level quality assurance before delivery
Filed and Confirmed
Submitted through your software, HMRC acceptance reference returned in writing
“Probal Global handles our entire CT600 preparation workload during the April and October filing peaks. The computations arrive reviewer ready with a clear open point log, our tax manager just signs off rather than preparing from scratch. We've saved over £30k annually and not once missed an HMRC deadline.”
£30k+
Annual saving on CT preparation
Built Around the April 2026 Penalty Regime, Not the Old One
The cost of a late CT600 doubled on 1 April 2026. For returns with a filing date on or after that day, HMRC charges £200 the day after the deadline and a further £200 at three months. Where a company has filed late three years running, those fixed penalties rise to £1,000 and £2,000, and they apply even when no corporation tax is due at all. The tax geared charges are unchanged: 10% of the unpaid tax at six months, another 10% at twelve.
Two things make that riskier than it reads. HMRC closed its free joint filing service on 31 March 2026, so every return now goes through commercial software, and a submission rejected on its iXBRL tagging does not count as filed. Late payment interest runs at 7.75% from 9 January 2026, charged daily from nine months and one day after the period end — three months before the return itself is due.
The rates themselves are steady: 19% up to £50,000, 25% above £250,000, and marginal relief between the two at a 26.5% effective rate on the slice, with both thresholds divided by the number of associated companies. We work to those figures as standard, which is why the corporation tax return UK practices send us comes back ready to sign rather than ready to check.
Probal Global vs Your Other Options.
See why UK practices choose dedicated outsourcing over internal preparation or freelancers — and how we compare with the other corporate tax outsourcing UK providers you are likely shortlisting.
Real questions from UK accountancy practices answered honestly.
If this is the first time you have looked at handing a corporation tax return UK client file to an outsourced team, you probably have a few questions. Here are the ones we get asked most, with straight answers.
Still have questions? Get in touchYes. We work directly inside your existing tax software so there is no migration and no disruption to your internal review workflow. We adapt to your file structures and templates from day one.
Yes. We prepare R&D computations including the technical narrative template, the qualifying expenditure schedule and the supporting documentation for the Additional Information Form. For accounting periods beginning on or after 1 April 2024 that means the merged R&D expenditure credit at 20%, or Enhanced R&D Intensive Support where a loss making company meets the 30% intensity test. The old SME and RDEC schemes now only apply to periods that began before 1 April 2024, and we still handle those where an amended claim is in date.
Capacity scales instantly. Most firms add dedicated CT resource from us during their spring and autumn peaks. Work is allocated the same day it arrives and turnaround is maintained at 5 working days.
Yes. We handle group relief surrenders, loss carry back and carry forward claims, and associated company rules including marginal relief calculations across the group.
We sign an NDA and DPA before any work begins. All files are transferred via encrypted channels. No client data is stored after delivery. We are GDPR registered and ISO 27001 aligned.
Revisions based on reviewer feedback are included at no extra charge. We aim to turn around revision files within 24 hours of receiving your comments.
Pricing is per return, based on complexity rather than headline volume. A dormant company and a trading group with R&D, group relief and associated company adjustments are not the same job. There is no retainer, no minimum volume, and the senior CA review is never charged separately. Send us five representative client files and we will price them properly rather than quote a rate that changes at month three.
A return rejected by HMRC's Business Validation Rules does not count as filed, even if it was submitted before the deadline. Since the fixed penalties doubled on 1 April 2026, that turns a tagging error into £200 on day one. We validate the iXBRL tagging and the computation against the return before anything is submitted, and we send you the HMRC acceptance reference in writing. If a submission is rejected on our work, we correct and resubmit at no charge.
No, and that is deliberate. We prepare the computation and the return. The tax advice UK clients receive stays with you, under your firm's name and your professional indemnity cover. We are not a UK tax consultant to your clients — we are the production team sitting behind yours. Where a computation raises a planning point, a loss to carry back, a marginal relief threshold within reach, or an associated company that changes the limits, it goes into the open point log for your reviewer to take forward as their own advice.
Free Trial Available
Try Probal Corporation Tax Free.
No Cost, No Commitment.
Send us a real client file. We will prepare the CT600 and computation in your software, return a reviewer ready pack in 5 working days, and let the quality speak for itself. It is the lowest risk way to test corporate tax services UK practices actually rely on before you commit a single client file to it.