The word ‘tan’ appears in its original form, and does not vary with context. There is no need to modify it according to gender, number, nor any other variable.
1. You-all are so wet (Uds.) están tan mojados 2. It is so difficult Es tan difícil 3. So sad Tan triste
The Word ‘Tanto’ is Matched to the Noun’s Gender and Number
Unlike the word ‘tan’, the word ‘tanto’ is matched to the noun’s gender and number. Thus, ‘tanto’ has four possible conjugations, as shown in the table above.
1. It is not so much No es tanto 2. So many people Tanta gente/Tantas personas 3. So much money Tanta plata