preposition: [in/for property tax] [in/for rent]

[ansonman]

I have made up the sentences below.

(1a) Jack purchased a computer from an overseas company. When he picked it up, he paid $100 in/for import duty.

(1b) Every month, Henry has to pay $1200 in/for rent.

Which preposition is correct? Thank you for your help.

[Alan]

'In' is correct in both.