Futur I and futur II

Futur I = ću, ćeš, će, ćemo, ćete, će + infinitive. Because ću is a clitic, it cannot start the sentence; there are three possible orders:

• Why “radit”? When ću follows the infinitive, the final -i drops. Infinitives in -ći don't change: Doći ću. Ići ću.
• Negative: neću + infinitive: Neću doći. — I won't come.
• Question: Hoćeš li doći? / Da li ćeš doći? — Will you come?
• Spoken variant (Serbia, Bosnia): ću da radim.

Futur II = budem, budeš, bude… + active participle. It is used only in a subordinate clause (after ako, kad, čim, dok…) for a future action, where English uses a present or present perfect.

• Ako budem imao vremena, doći ću. — If I have time, I'll come.
• Kad budeš završila, nazovi me. — When you've finished, call me.

With a perfective verb, the simple present is enough and more common: Ako dođeš, javi se. — If you come, let me know. Futur II is mainly useful with imperfectives and with biti, imati, moći: Ako budem mogao… — If I can…