Some protesters have rejected a new cabinet formed last week and accuse the political elite of ignoring demands that include an independent government and fighting corruption.
MPs are expected to vote on a budget that was first drafted by the Saad al-Hariri-led government that quit in October, prompted by the protests.
Parliament's finance and budget committee has introduced changes since then. Its chairman, Ibrahim Kanaan, told Reuters on Friday the latest projection was for a budget with a deficit of 7% instead of the originally hoped-for 0.6%, reflecting the crisis.