How to incorporate this date field in this current script

[trishita]

if (Match([Pensionseinrichtung],'HPK'), sum( total {$<Pensionseinrichtung={'HPK'}>} [HPV Buchwert]),

if (Match([Pensionseinrichtung],'HPR ALL'), sum( total {$<Pensionseinrichtung={'HPR ALL'}>} [HPV Buchwert]),

if (Match([Pensionseinrichtung],'HPR SMST'), sum( total {$<Pensionseinrichtung={'HPR SMST'}>} [HPV Buchwert]),

if (Match([Pensionseinrichtung],'HPR ZF'), sum( total {$<Pensionseinrichtung={'HPR ZF'}>} [HPV Buchwert]),'Unknown'

))))

I want to add a condition for a specific date given by the field Stichtag = 'Dez.2018'. How to incorporate this date field in this current script

[gbommisetti]

if (Match([Pensionseinrichtung],'HPK') and Stichtag = 'Dez.2018', sum( total {$<Pensionseinrichtung={'HPK'}>} [HPV Buchwert])