Public sector net borrowing (PSNB) rose £1.1bn in October compared with the same month a year ago to £8.2bn, official figures show.
That is the highest level of borrowing in October in six years.
The government has borrowed £54.3bn so far this year and is making slow progress on meeting the Office for Budget Responsibility (OBR) forecast.
These figures mean Chancellor George Osborne will need to restrict borrowing to just £15bn between now and April
While not impossible - January usually sees a surplus thanks to an influx of self-assessment income tax receipts - it remains unlikely that the chancellor will meet the £69.5bn OBR forecast without severe cuts at next week's Autumn Statement.
The previous annual borrowing figure was £90.1bn.
The Treasury said the figures showed the job of rebalancing the economy was "not yet done".