The taxpayer subsidised Parliament's exclusive bars and restaurants to the tune of £6 million last year.
While the bill fell in the House of Commons after a series of revenue-raising measures, costs at the Lords went up.
Usually the Commons publishes figures that offset sales of souvenirs and gifts against spending on its catering service.
But in response to a freedom of information request, the authorities revealed that without that income the operation ran a deficit of £4.5 million in 2013-14.
That was down from £4.9 million the previous year.
Meanwhile, the House of Lords annual accounts showed that the net cost of its catering and retail outlets rose by around £150,000 to £1.45 million.
Excluding profits from banqueting functions and retail sales, the overall bill was some £2.44 million - up from £2.3 million in 2012-13.
A Commons spokeswoman said: "Much of the net cost to the House arises because of the irregular hours and unpredictability of Parliamentary business.
"Food and drink prices are regularly reviewed and set at levels benchmarked against similar outlets outside the House.
"The costs to the House have been reduced since 2003.
"We are determined to reduce costs further and have a target of £3 million for 2015-16."