The road tax on personal cars has been abolished from the 2022 tax year. From 1st of January 2022, only selected vehicles weighing 12 tonnes or more are subject to the road tax.
If the road tax applies to you (e.g. you own a vehicle subject to road tax, especially trucks), the deadline for filing your tax return is the 31st of January of the following year, or the first working day after that date if the 31st of January falls on a weekend or holiday.