Practical compliance tool

CT600 Late Filing Penalty Calculator

Estimate the standard CT600 late filing penalty from the filing deadline, actual filing date, and repeat-default position.

This is designed to help you gauge the filing consequence quickly once the CT600 deadline and the actual submission date are known.

CT600 Late Filing Penalty Calculator

Estimate the standard CT600 late filing penalty from the filing deadline, actual filing date, and repeat-default position.

Was the previous return also late?

What the CT600 penalty result is showing

The result estimates the standard late filing position for the Company Tax Return using the deadline, delay, and repeat-default status.

It helps you separate the return-filing consequence from the separate payment and interest issues that can exist alongside it.

Rule summary

CT600 late filing at a high level

Late CT600 filing penalties increase as the delay becomes longer and can become more severe where there is a repeated default history.

The return deadline must be identified correctly first, otherwise the penalty estimate will be built on the wrong date.

Worked examples

How the result behaves in practice

Short filing delay

A CT600 is filed shortly after the standard deadline with no repeated default pattern.

The estimate stays closer to the lower end of the standard filing-penalty scale.

Repeat late return

A return is filed late and the company also has a recent history of late Corporation Tax returns.

The estimate becomes more serious because repeat default affects how the filing failure is viewed.

Turn the result into an action plan

Confirm the CT600 filing deadline before relying on the penalty estimate.

If payment was also late, pair this with the Corporation Tax interest and late-payment tools.

Where there is a reasonable excuse case, move into the HMRC appeal path rather than treating the estimate as the final outcome.

Read the guide

CT600 late filing penalties

This guide explains the practical late-filing consequences for a CT600 return and why repeat default history changes the risk profile.

Assumptions and limits

This tool gives a practical estimate and depends on the assumptions shown below.

Assumptions

  • The inputs entered are complete and reflect the facts for the relevant filing, tax, or compliance period.
  • The tool is used for a standard scenario rather than a specialist exception, relief, or disputed case.

Limits and rule basis

  • This tool does not replace detailed professional review where the facts are unusual or contested.
  • If the underlying rule depends on reliefs, appeals, or special handling, the real outcome may differ.