HMRC will charge you a penalty for late submission and/or payment.
The penalties increase the longer the returns or payment remain outstanding.
The tax year runs from 6th April to 5th April each year.
The Self Assessment and any tax and National Insurance due to HMRC must be submitted by the 31st January of the following year. This is the last deadline for filing electronically.
Self Assessment is a means of declaring your income, costs and profits to HMRC, for anybody that earns income outside of the PAYE system.
Once your full income for the year has been established, with costs and any tax deducted at source omitted, the tax and National Insurance due on your taxable profits can be calculated.
The requirements to comply with HMRC regulations are generally that you must pay your Corporation Tax bill within 9 months of the end of your financial year, and then file your company Tax Return within 12 months of the end of your financial year.
The rules are more complex with those who do not have accounts spanning a period of 12 month or have high levels of Corporation Tax liabilities.
There are, of course, penalties for late filing of Corporation Tax returns and for those who pay Corporation Tax late.
Corporation Tax is a tax on the taxable profits of limited companies and other organisations including sports clubs, societies, associations and other certain unincorporated businesses.