Gordon Brown spent £732 on 250 refill cartridges for his favourite black pens shortly before stepping down from the Commons.
Details of the bill emerged as the Independent Parliamentary Standards Authority (Ipsa) begins publishing MPs' expenses receipts after losing a landmark freedom of information battle.
Three receipts at the centre of a protracted legal battle - relating to claims by Speaker John Bercow, George Osborne and Alan Keen - were released last month following a ruling by the Court of Appeal.
The latest document is the first to be disclosed under FOI without a court ordering it.
It shows that Mr Brown bought 250 black ink refill cartridges for a Cross Porous point pen in December last year.
The total cost including VAT was £732.
The former prime minister - who stepped down from parliament three months later at the general election - is believed to have favoured the pens and used them to make copious notes on official documents.
David Cameron's team reportedly found mystery deep scratches on an antique mahogany desk in Downing Street in 2010, which were blamed on Mr Brown's aggressive writing style.