The horse tram service made a loss of almost half a million pounds last season.
Figures were revealed by public transport bosses in response to a Freedom of Information request.
They show that the Douglas bay tramway generated revenue of £142,703 in 2017 - but cite running costs as £626,002, leaving a deficit of £483,299.
The government took over the horse trams in 2016 when Douglas Council pulled the plug on the loss-making service.
At that time, the council cited estimated operating costs for 2016 of £263,000 as the reason for its decision.
Then infrastructure minister Phil Gawne said costs were reduced by operating a revised timetable and extending the length of the season, the potential deficit being just under £100,000 for that first season under government control.
But the FoI response states that running costs last year totalled £626,002.
It says this figure comprised capital expenditure - the purchase of assets, fixtures and fittings from Douglas Council and horse tram refurbishment - revenue expenditure (rent and payroll), and other expenditure (purchase of horses and other equipment).
Figure also includes out-of-season running costs.
Revenue generated last year was just £142,703 which includes a proportion of takings from Explorer tickets.
This proportion is the same as that previously paid to Douglas Borough Council when the tramway was under its ownership.
The horse tramway saw a 6% increase in passengers in 2017 with numbers for single journeys rising from 69,702 in 2016 to 73,954 last year.
Plans have been submitted for a £1.5m project to demolish and rebuild the Strathallan horse tram depot (18/00305/GB).
Separate planning permission is being sought for temporary stables for the tram horses on the Summerland site.
A second, smaller, proposal for temporary stables was approved in December but an appeal was launched against it.