She has requested the Office for Budget Responsibility to prepare an independent forecast to accompany the Budget.
Reeves acknowledged the economy is not working well enough and pledged a tight grip on spending to curb inflation and borrowing costs.
The Chancellor is widely expected to have to raise taxes to address a potential £51 billion shortfall in the nation's finances.
Her priorities include fixing economic foundations, controlling day-to-day spending, and fostering investment and reform to build an economy that benefits working people.