You are kidding, surely.
For starters, N-regs do not have an expiring CofA.
I'm not kidding.
Italian microlights are exempt because they are not on the Italian register and AOPA Italy has asked the tax authorities to confirm that the tax does not apply to Permit to Fly aircraft, since the wording only refers to the validity of a CofA.
Unfortunately, the authorities have 6 months to respond, which could mean waiting until August.