Business owners are under the obligation to satisfy the “time criterion” in order for them to be eligible for specific tax allowances such as retirement reserve, tax relief for the self-employed, co-working partner’s relief and allowance for research and development work.
The criterion is that you should devote at least 1,225 hours per calendar year to activities relating to your business. The definition of activities in aid of your business’ commercial interests is broadly based, including as it does the time you may spend commuting, attending courses for professionals in your particular field or building your web site.
As for the evidence bearing out that you have devoted at least 1,225 hours per annum to your business, this is pretty straightforward if your business has been up and running for some time and you don’t have any other professional activities. If you do, however, e.g. in paid employment, this makes it all the more important to keep close track right from the start of hours worked for your own business!