Accountant vs DIY CT600: Which Is Right for You?

Every UK company must file a CT600, but should you pay an accountant or do it yourself? The answer depends on your company's complexity, your confidence with numbers, and what you value most.

The Quick Decision

FactorHire AccountantDIY Filing
Company typeComplexSimple
Your timeLimitedAvailable
Your confidenceLowMedium-High
BudgetFlexibleTight
ComplexityR&D, groups, lossesTrading, dormant

Cost Comparison

Accountant Costs

Service LevelTypical Cost
CT600 only£200-400
CT600 + accounts£400-800
Full service (bookkeeping included)£800-2,000+
Prices vary significantly by location and firm size.

DIY Costs

OptionCost
TinyTax (micro-entity)Free
Paid CT600 software£50-150/year
Your time2-4 hours

5-Year Cost Comparison

For a typical micro-entity:

ApproachAnnual Cost5-Year Total
Basic accountant~£400£2,000
Full-service accountant~£1,000£5,000
DIY with TinyTax£0£0
Potential saving: £2,000-5,000 over 5 years

When to Use an Accountant

Definitely Use an Accountant If...

  • You have R&D tax credit claims
  • Your company is part of a group
  • You have complex loss situations
  • You're claiming patent box relief
  • You have significant transactions with overseas entities
  • Your turnover exceeds £1 million
  • You're unsure about tax planning opportunities

Consider an Accountant If...

  • You have no time to learn the process
  • You're anxious about getting it wrong
  • Your accounting records are messy
  • You want someone to check your work
  • You value the relationship for advice

When to File Yourself

Definitely DIY If...

  • You're a micro-entity (most small companies)
  • Your company is dormant
  • You have straightforward trading
  • Your records are organised
  • You're comfortable with basic numbers
  • You want to save money

DIY Is Easier Than You Think

With modern software like TinyTax:

  • No accounting knowledge required
  • Step-by-step guidance throughout
  • Automatic tax calculations
  • Direct HMRC submission
  • Built-in error checking
Most people can file their first CT600 in under an hour.

What Each Approach Involves

Using an Accountant

You provide:

  • Bank statements
  • Invoices and receipts
  • Expense information
  • Any other financial records
They handle:
  • Bookkeeping (if included)
  • Accounts preparation
  • CT600 completion
  • HMRC submission
  • Companies House filing
  • Queries from HMRC

DIY Filing

You do:

  1. Gather your financial records
  2. Enter figures into software
  3. Review the calculations
  4. Submit to HMRC
  5. File to Companies House
  6. Pay any tax due
Software does:
  • Tax calculations
  • iXBRL accounts generation
  • Validation checks
  • Submission to HMRC/CH

Real Time Comparison

Accountant Route

StepYour TimeElapsed Time
Gather records1-2 hoursDay 1
Send to accountant15 minutesDay 1
Answer queries30 minutesDays 2-7
Review and approve30 minutesDays 7-14
Total your time2-3 hours1-2 weeks

DIY Route

StepYour TimeElapsed Time
Gather records1-2 hoursDay 1
Enter into software1-2 hoursDay 1
Review and submit30 minutesDay 1
Total your time2.5-4.5 hoursSame day
DIY takes slightly more of your time but is completed much faster.

Risk Assessment

Risks of DIY

RiskLikelihoodMitigation
Making errorsLow-MediumSoftware validation
Missing deductionsMediumChecklists, guides
HMRC enquiryVery LowAccurate filing
Late filingLowCalendar reminders

Risks of Using an Accountant

RiskLikelihoodMitigation
High feesMediumGet quotes
Communication delaysMediumClear deadlines
Errors (yes, they happen)LowReview before signing
Still liable (you sign off)100%Understand what you're approving
Important: Even if an accountant prepares your CT600, you're legally responsible for its accuracy.

The Hybrid Approach

Many directors choose a middle ground:

DIY + Accountant Review

  1. Prepare your own CT600 using software
  2. Pay an accountant to review before submission
  3. Submit yourself
Cost: £100-200 for review only

DIY + Annual Consultation

  1. File your own CT600
  2. Have an annual meeting with an accountant for tax planning advice
  3. Ask questions as they arise
Cost: £150-300 for annual consultation

Frequently Asked Questions

What if I make a mistake?

You can amend your CT600 within 12 months of the filing deadline. Genuine mistakes rarely result in penalties.

Do accountants actually find tax savings?

For simple companies, rarely. Most savings come from complex planning (R&D, investment structures) that don't apply to micro-entities.

What do accountants actually do?

For a basic filing: enter your figures into their software, check for obvious errors, submit. Similar to what you'd do yourself.

Am I qualified to file my own CT600?

There's no qualification required. If you can manage your business finances, you can file a CT600.

What if HMRC asks questions?

You can handle routine queries yourself. For complex issues, you can engage an accountant then if needed.

Making Your Decision

Choose an Accountant If...

You answered "yes" to any of these:

  • My company has complex tax claims
  • I genuinely have no time
  • I'm anxious about tax compliance
  • I want ongoing advisory support
  • My turnover exceeds £1 million

Choose DIY If...

You answered "yes" to most of these:

  • I'm a micro-entity with simple affairs
  • I want to save money
  • I'm comfortable with basic numbers
  • My records are reasonably organised
  • I'm willing to spend a few hours learning

Summary

FactorAccountantDIY
Cost£400-1,000+/year£0-150/year
Your time2-3 hours3-5 hours
Complexity handledAll levelsSimple to moderate
ControlLessMore
LearningMinimalSome
Speed1-2 weeksSame day
For most micro-entity companies, DIY filing with software like TinyTax offers significant cost savings with minimal additional effort.

Related guides:

  • Free CT600 Filing
  • CT600 Software Guide