(Reuters) - The U.S. Treasury said on Monday it plans to borrow $463 billion in the second quarter, more than the February estimate of $95 billion, as it increases spending in response to COVID-19. The second-quarter estimate assumes an end-June cash balance of $800 billion, the Treasury said in a statement. It comes after the Treasury in February slashed its borrowing projections for the first and second quarters as part of a plan to reduce its cash balance. The Treasury said it issued $401 billion in net debt in the first quarter, ending the three-month period with a cash balance of $1.122 trillion. It expects to borrow $821 billion in the July to September quarter, assuming an end-of-September cash balance of $750 billion. Reporting By Karen Brettell; Editing by Chris Reese Our Standards: The Thomson Reuters Trust Principles.