In this article, we report new marine reservoir age correction (ΔR) values from the Marine20 calibration for the Penghu Islands in the Taiwan Strait over the past 6700 cal BP, derived from 14C and U-Th ages of Holocene corals. Since secondary calcite from diagenetic processes can influence coral 14C ages, we developed a pretreatment protocol that ensures low calcite content (<1%, 0.8±0.2%) using a combination of thorough physical cleaning and repeated XRD measurements. We compare our new measurements with published ΔR values from the region, recalculated to conform to the Marine20 dataset. The results show larger temporal variation (∼300 yr) in ΔR from 5500 to 6700 cal BP for the Penghu Islands and ∼400 yr variability at several SCS sites from 5500 to 8200 cal BP. Relatively smaller ΔR variability is observed from 0–5500 cal BP: ∼220 yr in the Penghu Islands and ∼320 yr for South China Sea sites. The weighted mean ΔR value of –155±59 14C yr for the past 5500 cal BP is determined as the marine reservoir age correction around Taiwan and northeastern SCS, and this value is consistent with modern values inherited from the North Equatorial Current, the upstream source of the Kuroshio Current that feeds the northeastern SCS and the Taiwan Strait.