This paper presents the characterization and modeling of microwave passive components in TSMC 40-nm bulk CMOS, including metal-oxide-metal (MoM) capacitors, transformers, and resonators, at deep cryogenic temperatures (4.2 K). To extract the parameters of the passive components, the pad parasitics were de-embedded from the test structures using an open fixture. The variations in capacitance, inductance and quality factor are explained in relation to the temperature dependence of the physical parameters, and the resulting insights on the modeling of passives at cryogenic temperatures are provided. Modeling the characteristics of on-chip passive components, presented for the first time down to 4.2K, is essential in designing cryogenic CMOS radio-frequency integrated circuits, a promising candidate to build the electronic interface for scalable quantum computers.