Vermögensverwaltungskosten pauschal: including 3a-invested capital?

The pauschal deduction for Vermögensverwaltungskosten is computed over the total securities one owns (the deduction amount is for instance 0.3% in canton ZH). But should one be able to include 3a-invested capital (say via VIAC) in this securities total? The argument in favor would be that one also pays verwaltungskosten in that case.

Deductions apply to amounts that are actually subject to taxation (hence the name “deduction”). 3a and vested benefits amounts and gains are not taxed (until withdrawal)…