WASHINGTON — The federal government recorded a deficit of $107.1 billion in August, slightly lower than the July deficit. But the imbalance through 11 months of this budget year is up sharply from a year ago, reflecting higher spending and lower-than-expected tax revenues.

The Treasury Department said Tuesday that the deficit, with just one month to go in the budget year, totals $620.8 billion, up 17.1 percent from the same period a year ago. The August deficit was slightly lower than the $112.8 billion imbalance in July.

The Congressional Budget Office last month revised its estimate for the 2016 deficit up sharply to show an imbalance of $590 billion. That was up from a March projection of $534 billion. The budget year ends on Sept. 30 and September is expected to show a surplus.

The CBO estimate for the 2016 deficit is close to the $599.9 billion deficit that the Obama administration estimated when it released its mid-session budget review in July. Both projections are about one-third higher d but it is about one-third higher than the actual deficit in 2015 of $439.1 billion, the lowest deficit in eight years.

Through the first 11 months of this budget year, revenues total $2.91 trillion, a modest 0.9 percent higher than the same period in 2015, while outlays total $3.53 trillion, up 3.4 percent from the same period in 2015.

The CBO sees steadily rising deficits over the next decade, reflecting higher Social Security and Medicare payments as baby boomers retire. But because CBO in its latest report projected that economic growth will be slower, it expects that interest rates over the next decade will remain lower as well. That means the government will have to spend less to finance the debt.

CBO projected that deficits over the next decade will be $712 billion lower than it projected in March. That would still add up to $8.57 trillion being added to the national debt over that period. The debt at present stands at $19.4 trillion.