Modal-like expressions of obligation/necessity:
- Present: have to / has to + base verb (e.g., "I have to study," "She has to leave.")
- Past: had to + base verb (e.g., "We had to wait.")
- Future: will have to + base verb (e.g., "You will have to finish it.")
The phrase "last year" clearly signals the need for a past tense construction.