Commuters' contributions to the cost of the rail system have been laid bare in new figures.
Some of the lines with the busiest routes into London made tens of millions of pounds for the taxpayer last year - while others required hundreds of millions of pounds in subsidy.
Overall, the public purse pumped £2.3 billion into the rail system in 2013-14 - down from £3.2 billion in 2009-10 as the Government shifted more of the burden to travellers.
The breakdown of subsidy levels for each train operating company emerged after it was announced that regulated fares are due to go up by an average of 3.5% next year.
According to the DfT figures, the most heavily subsidised operator last year was Northern Rail, which received a net injection of £707 million.
That equated to a subsidy per passenger mile of 51.5p.
CrossCountry received £315 million overall - giving a subsidy per passenger mile of 15.6p.
By contrast South West Trains returned a surplus of £64.1 million, 1.7p for every passenger mile travelled.
The public purse was £93.7 million in the black from its dealings with First Capital Connect - 3.9p per passenger mile - and East Coast had a £19.9 million surplus, equivalent to 0.6p per passenger mile.
Here is a breakdown of subsidy levels for train operating companies. The DfT figures include spend on Network Rail maintaining track.
Train operating company - taxpayer subsidy/(surplus) - subsidy/(surplus) per passenger mile
c2c - £36.5 million - 5.6p
Chiltern Railways - £58.6 million - 7.9p
CrossCountry - £315.3 million - 15.6p
East Coast - (£19.9 million) - (0.6p)
East Midlands Trains - £182.2 million - 13.1p
First Capital Connect - (£93.7 million) - (3.9p)
First Great Western - £230.3 million - 6.4p
First TransPennine Express - £173.7 million - 16.8p
Greater Anglia - £41.6 million - 1.5p
London Midland - £199.2 million - 13.6p
Northern Rail - £707.3 million - 51.5p
Southeastern - £334.3 million - 12.4p
Southern - £17 million - 0.6p
South West Trains - £64.1 million - 1.7p
Virgin Trains - £180.1 million - 4.7p
Total subsidy for all DfT franchised train operating companies: £2.3 billion, 6.8p per passenger mile.
The Rail Delivery Group, which represents train operators and Network Rail, said: "Phenomenal growth in rail passengers is helping train operators to pay £2 billion a year back to government - five times more than 15 years ago - with government choosing to reinvest this money in further improving Europe's best network.
"Government support for the industry is declining and per journey is the same or lower than in nine of the last 12 years leading up to privatisation."
Mick Cash, acting general secretary of the RMT union, said: "Whichever way these numbers are carved up and spun, they show that rail franchising is a one-way ticket to the bank for the private train companies. You either make a fat profit and, if you don't, the taxpayer is forced to cough up huge subsidies to keep the company boardrooms awash with cash.
"The figures show a 7.5% fall - nearly £130 million - in the amount paid back by franchise holders to the Government while revenue support payments to the private train companies have increased by 54% since 2011-12, from £489.6 million to £753.1 million.
"With another windfall heading their way from the inflation-busting rise in fares, it is no wonder that the British people are sick of these scroungers and parasites milking our railways for their own benefit."
Shadow transport secretary Mary Creagh said: "Britain's rail fares are among the highest in Europe, which is why a Labour government will review the Government's failed franchise system, after the chaos of recent years, to put the passenger and taxpayer first.
"Only a Labour government will ease the pressure on fare payers by capping annual fare rises on every route, simplifying fare structures and creating a new legal right to the cheapest ticket."
A DfT spokeswoman said: "Passenger numbers are at record high levels and this growth is expected to continue. This is why over the next five years more than £38 billion will be spent on the railways to increase the capacity and quality of the network.
"Our rail franchising programme has brought significant benefits to passengers and the taxpayer. This includes money some franchises are able to pay back to government, but this does not mean there is a profit margin that could reduce fares.
"The UK Government provided more than £2 billion of net subsidy in 2013/14, helping keep trains running right across the country.
"We recognise the impact of travel costs on family budgets, which is why we reduced average regulated fare rises to RPI plus 0% this year for the first time in a decade."