CT600 Box 300: Profits Chargeable to Corporation Tax

Box 300 on the CT600 shows profits chargeable to Corporation Tax. This is the final profit figure that your company pays tax on - after all deductions and reliefs have been applied.

What Goes in Box 300?

Box 300 is typically the same as Box 235 (Total profits) for most companies. It represents your taxable profit - the amount on which Corporation Tax is calculated.

For most small companies:

  • Box 300 = Box 235
  • This is your profit after all deductions
The figure in Box 300 is what you pay Corporation Tax on.

How Box 300 Is Calculated

The Standard Calculation

For most companies:

``` Box 215 (Gross profits)

  • Box 220 (Losses brought forward)
  • Box 225 (Losses carried back)
  • Box 240 (Non-trade deficits)
  • Box 245 (Property losses)
  • Box 250 (Management expenses)
  • Box 275 (Intangible losses)
  • Box 285 (Trading losses against other profits)
  • Box 295 (Charitable donations)
= Box 300 (Profits chargeable) ```

Simplified Example

BoxDescriptionAmount
215Gross profits£80,000
220Losses brought forward(£10,000)
295Charitable donations(£2,000)
300Profits chargeable£68,000

Box 300 vs Box 235

For most companies, these boxes show the same figure:

BoxDescription
235Total profits (after deductions)
300Profits chargeable to CT
When they differ:
  • Ring-fenced profits (oil & gas)
  • Northern Ireland profits (special rate)
  • Other exceptional circumstances
For typical small companies: Box 300 = Box 235

The Journey to Box 300

Starting Point

Box 215 includes all income:

  • Trading profits (Box 165)
  • Property income (Box 190)
  • Chargeable gains (Box 210)
  • Other income

Deductions Applied

Various reliefs reduce Box 215 to reach Box 300:

  • Loss reliefs
  • Charitable donations
  • Management expenses
  • Group relief

Final Figure

Box 300 is what remains - your taxable profit.

Why Box 300 Matters

Corporation Tax Calculation

Box 300 directly determines your tax:

Small Profits Rate (19%):

  • Profits up to £50,000
  • Tax = Box 300 × 19%
Main Rate (25%):
  • Profits over £250,000
  • Tax = Box 300 × 25%
Marginal Relief:
  • Profits between £50,000 and £250,000
  • Effective rate between 19% and 25%

Example Tax Calculations

Box 300RateTax
£40,00019%£7,600
£100,000Marginal~£21,250
£300,00025%£75,000

Special Cases

Ring-Fenced Profits

Companies in oil and gas may have:

  • Ring-fenced profits (Box 305)
  • Taxed at different rates
  • Separate from main Box 300

Northern Ireland Rate

Companies qualifying for NI rate:

  • May have profits split
  • Different rates apply
  • Specialist treatment needed

Small Company: Simple Case

For most readers:

  • No ring-fence profits
  • No special rates
  • Box 300 = Box 235 = Taxable profit
BoxDescription
235Total profits
295Charitable donations
300Profits chargeable (this box)
305Ring-fence profits
315Corporation Tax due

Common Questions

Why might Box 300 differ from my accounts profit?

Tax adjustments create differences:

  • Disallowable expenses (entertaining, depreciation)
  • Capital allowances (different from depreciation)
  • Timing differences
  • Tax-specific reliefs

Can Box 300 be zero?

Yes. If deductions exceed income:

  • Loss-making company
  • High charitable donations
  • Significant loss reliefs
No tax due if Box 300 is zero.

What if I made a loss?

If you have a loss:

  • Box 300 = £0
  • No tax to pay
  • Loss carries forward or back

How does Box 300 relate to what I pay HMRC?

Box 300 × Tax Rate = Corporation Tax due

The tax is then shown in Box 315.

When Using TinyTax

TinyTax calculates Box 300 automatically:

  1. Enter all income and expenses
  2. Apply available reliefs and deductions
  3. Box 300 is calculated
  4. Tax is computed on this figure
No manual calculation needed - the software handles everything from gross profits to tax due.

Need Help?

TinyTax calculates your profits chargeable to Corporation Tax automatically. Enter your figures and the software does the rest.

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