It's not that clear. Here's a good explanation: http://www.economist.com/.../parliamentary-procedure

It's true that you cannot filibuster a budget resolution in the Senate, because the Budget Act provides special rules for consideration of a budget resolution, including a time limit on debate. So the Senate can pass a resolution with only a majority vote. However, the resolution does not take effect when the Senate passes it. It takes effect in one of two ways: if the House and Senate pass an identical resolution, usually in the form of a conference report; or if the Senate passes a separate Senate Resolution (as opposed to a concurrent resolution, which is what a budget resolution is) that says the House is “deemed” to have agreed to the budget resolution passed by the Senate.