Treatment of German health insurance deductions

Interesting means testing question.  I am hoping there might be some on-point case law, but struggling to frame my search criteria with sufficient precision for the UT websites.

HB claimant in receipt of German retirement pension from which there is a compulsory deduction of 170 euros a month for sickness insurance.  Right to reside not an issue, hence me choosing this board to post the query.  How should the deduction be treated?

Reg 33(12) of the HB(SPC) Regs says that any amount payable by way of “tax” is disregarded from the claimant’s income.  The Regulations do not, as far as I can see, further define “tax”, so one option is to say that the contribution is analogous to tax.  I wondered whether Article 5 of the coordination regulation might provide some support for that approach, but I feel that is a blind alley because (i) HB is not within the scope of the coordination regulation and (ii) Article 5 only works from the point of view of the competent state dealing with facts and events in another member state.  In this case, Germany is the competent state for pension and sickness insurance and no coordination issue arises from the point of view of the UK.

Any better arguments, or UT cases, about how such deductions should be treated for the purpose of UK means tested benefits?