Pay federal tax in installments?

Just got a fat Bundessteuer bill from the Zurich tax office and, for the first time, I noticed it says I can ask to pay it in instalments, which would be something interesting for me to do at this moment (but I guess they’ll check my finances and deny it). Anybody knows whether they’d make me pay interests and how much? I couldn’t find this information on the Zh tax office website.

Looks like 4% starting April 1. Up to 12 instalements for the provisional tax bill in case of difficulty to settle by March 31.

They don’t give details on the criterias to meet and there is a form to complete.