I don't need an environmental permit, what do I fill in for that question

No permit requirement is a valid answer to the permit question

"No, not subject to permitting" is just as valid an answer as "yes, permit present" for does the enterprise have the required environmental permits?. The question in most VSME-like lists asks whether the activity is subject to permitting and, if so, whether that permit is present and valid. If your business falls under a notification requirement instead of a permit requirement — think of an activity under the Activities Decree-like regime of the country where you are established — then "no permit needed" is the factually correct state of affairs, not an omission you need to obscure.

So do not fill in "n.a." or "not applicable" if the answer is actually "no, not subject to permitting, but notified": those are two different situations and your customer cannot work with them if you merge them. In the explanation, briefly state which regime applies (notification, general rules, or exemption) and if necessary a reference to the decision or notification itself as supporting evidence. If you have no document showing the exemption — for example confirmation from the municipality or environmental authority that no permit is required — then "no, no permit, supporting evidence to follow" is more honest than a bare "no" without explanation. The same precision applies incidentally to are there facilities in or next to a protected natural area?: there too "no" is only strong if you know what that conclusion is based on, not if it is an assumption.

Where this comes from: VSME environmental module and the GHG Protocol as a framework

The VSME baseline module of EFRAG asks about permits within the environmental theme, as part of indicators on pollution and compliance; the GHG Protocol plays no role here, as it only governs the classification of greenhouse gas emissions into scope 1, 2 and 3, not permit requirements. The justification for "no permit needed" thus lies not in an emission standard but in the national or regional environmental legislation that determines whether your activity falls under a permit, a notification, or general rules — and that is a different source than the questionnaire itself.