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's (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".
It added that "government borrowing remains too high".
Borrowing warnings
Many economists say the Treasury has no hope of meeting the OBR's forecast for this year.
Howard Archer chief UK and European economist at IHS Global Insight said: "George Osborne now has an almighty task to meet his fiscal targets for 2015/16.
"Indeed, if the pattern of the first seven months of the fiscal year continued, PSNB would amount to £80.3bn in 2015/16, which would mean that Mr Osborne would overshoot by some £11bn the target of £69.5 billion contained in his July budget."
Ruth Miller, UK economist at Capital Economics, is also forecasting borrowing this year of £80.3bn and says today's figures leave the Chancellor "with less room for manoeuvre" in next week's Autumn Statement.
Government borrowing in the 12 months to October stood at £70bn taking the total national debt now to £1.5 trillion, or 80.5% of the UK's annual economic output