The hydrogen isotopic compositions of the leaf-wax n-alkanes (δD_alk) and n-alkanoic acids (δD_acid) are known to reflect ambient climatic conditions (including precipitation δD values, δD_Precip). However, the climatic conditions of exactly which period (i.e. early or entire period of the leaf’s lifespan) these biomarkers represent, i.e. the seasonality in δD_alk and δD_acid records, is still evolving. The seasonality studies on the δD_alk and δD_acid values, done only in extra-tropical regions, mostly indicate the δD_alk values are biased towards the early growing season whereas δD_acid values are not biased towards any season. To decipher the seasonality in the δD_alk and δD_acid records from the tropics, we conducted a long-duration experiment wherein deciduous and evergreen species were grown using normal water (δD = −2‰) during the early stages of the leaf's growth and later using isotopically-labeled water (δD = 1000‰). Our experiment revealed (i) in deciduous and evergreen species, δD_alk and δD_acid values reflect δD_Precip during the early stages of the leaf's growth, (ii) synchronous synthesis of n-alkanes and n-alkanoic acids, and (iii) in deciduous species, minor incorporation of the previous year’s photosynthates in the leaf wax pool of the current year’s mature leaves. Our study suggests that the δD_alk and δD_acid records in the tropics are biased towards the climatic conditions prevailing during the early stages of the leaf's growth. This bias should be considered while comparing the δD_Precip values generated from the leaf wax proxy records and isotope-enabled atmospheric circulation models.