(10)This Directive should ensure that the requirements for small undertakings are to a large extent harmonised throughout the Union. This Directive is based on the "think small first" principle. In order to avoid disproportionate administrative burdens on those undertakings, Member States should only be allowed to require a few disclosures by way of notes that are additional to the mandatory notes. In the case of a single filing system, however, Member States may in certain cases require a limited number of additional disclosures where these are explicitly required by their national tax legislation and are strictly necessary for the purposes of tax collection. It should be possible for Member States to impose requirements on medium-sized and large undertakings that go further than the minimum requirements prescribed by this Directive.