I was looking through the Historical Tables from the Office of Management and Budget (https://www.whitehouse.gov/omb/historical-tables/). I noticed that each year the debt increases by a different amount than the deficit. Why is this?
+------+---------------+---------------+---------------+
| Year | Gross Federal | Gross Federal | Deficit (From |
| | Debt (From | Debt | Table 1.1) |
| | Table 7.1) | Difference | |
+------+---------------+---------------+---------------+
| 2008 | 9,986,082 | | 458,553 |
+------+---------------+---------------+---------------+
| 2009 | 11,875,851 | +1,889,769 | 1,412,688 |
+------+---------------+---------------+---------------+
| 2010 | 13,528,807 | +1,652,956 | 1,294,373 |
+------+---------------+---------------+---------------+
| 2011 | 14,764,222 | +1,235,415 | 1,299,599 |
+------+---------------+---------------+---------------+
| 2012 | 16,050,921 | +1,286,699 | 1,076,573 |
+------+---------------+---------------+---------------+
| 2013 | 16,719,434 | +668,513 | 679,775 |
+------+---------------+---------------+---------------+
| 2014 | 17,794,483 | +1,075,049 | 484,793 |
+------+---------------+---------------+---------------+
| 2015 | 18,120,106 | +325,623 | 441,960 |
+------+---------------+---------------+---------------+
| 2016 | 19,539,450 | +1,419,344 | 584,651 |
+------+---------------+---------------+---------------+
| 2017 | 20,205,704 | +666,254 | 665,446 |
+------+---------------+---------------+---------------+
| 2018 | 21,462,277 | +1,256,573 | 779,138 |
+------+---------------+---------------+---------------+
As you can see the increase in the debt is different than the deficit and tends to be greater.
I found this article from Forbes by Stan Collender that seems like it is relevant.
In it he says
But even though the budget only shows the expected losses, the government still has lend the full amount cash of the loans being extended. Stan Collender, Forbes
Later he says
That means the government must borrow the funds even though it doesn't need them to finance the deficit. Stan Collender, Forbes
If I understand this correctly Stan Collender is saying the US Government has to loan more money that in needs to cover the deficit. Why would the US Government borrow more than it needs to cover the US deficit? What determines how much the US Government borrows?