What duration can or should I choose when applying for a Doc.CH grant?

Doc.CH grants are awarded for a minimum of 24 months up to a maximum of 48 months and doctoral students can be funded by SNSF grants for a maximum duration of 4 years, starting from the date of their registration as a doctoral student. If you will already be registered as a doctoral student for more than 2 years on the scheduled start date of the Doc.CH grant, then you may not apply for such a grant. However, in response to a written request giving reasons, the eligibility period for the submission of an application may be extended by a maximum of 1 year (see Clause 1.11 of the General implementation regulations for the Funding Regulations). Furthermore, in your Doc.CH grant application, you need to request the entire duration (first and second part of the grant pursuant to Article 2 of the Doc.CH Regulations). In principle, no further application for a supplementary grant to extend the duration of the grant may be submitted at a later stage (see Article 10 paragraph 4 of the Doc.CH Regulations). In other words, it is better to plan a feasible dissertation project with an adequate funding period than an overambitious project with a funding period that is too short (e.g. only 3 years are requested even though 4 years would be permissible under the Doc.CH Regulations as well as necessary to complete the planned research); dissertation projects whose duration is shorter than the longest permissible funding period pursuant to the Doc.CH Regulations are not more likely to be approved.