Microsoft, which has historically avoided borrowing money, this morning took the next step in its previously announced plan to raise funds through a public debt offering. The company made the move in a preliminary prospectus filed with the Securities and Exchange Commission.

The prospectus doesn't disclose the amount to be raised via the long-term notes, but the Microsoft board has authorized up to $6 billion in debt financing. The company has already issued $2 billion in commercial paper, a shorter-term form of debt, leaving $4 billion to go under that authorization. Bloomberg News, citing an anonymous person familiar with the situation, reports the total will be $3.75 billion.

Reports Bloomberg News' Dina Bass: "The sale will be split among $2 billion of 5-year notes, $1 billion of 10-year debt, and $750 million 30-year bonds, according to a person familiar with the offering who declined to be identified because terms aren’t set. The debt is expected to price as soon as today, the person said."

Microsoft had more than $25 billion in cash and short-term investments as of March 31, so it's not exactly hurting for money. The prospectus says the company will use the proceeds "for general corporate purposes, which may include funding for working capital, capital expenditures, repurchases of our capital stock and acquisitions."

That last part is stirring lots of speculation, with Reuters pointing to business software giant SAP as a possible Microsoft acquisition target. Of course, there's always the possibility of a Yahoo deal or partnership to consider. But others are hoping the company will use the funds to buy back more of its own shares, reaccelerating an initiative that has been under way for a few years.