Clubs could be banned from European competition from the 2014/15 season onwards if they do not comply with new financial rules.
The rules state clubs must break even over a three-year period.
Club owners will be allowed to put in up to €15million a year but only as equity, not a loan. This figure will then drop to €10million annually.
Clubs will be able to spend as much as they want on stadiums, training facilities and youth football.
UEFA will have a range of sanctions from warnings to a transfer ban to exclusion from European tournaments.
Across Europe, total club income in 2009 rose 4.8% to €11.7billion, but expenditure was a 9.3% increase to €12.9billion, making a €1.2billion deficit.
Most of the expenditure goes on player wages and one in three European clubs spent 70% or more of their income on salaries.
56% of European clubs ended 2009 in the red.
One in four clubs spent €6 for every €5 they earned.
A drop in transfer activity has reduced income by 5% to clubs in Scotland, France, Portugal and Holland.
English top-flight clubs are comfortably the richest in Europe with average revenue of €122million - five times higher than Holland and Russia.
Germany is second with average earnings of €86million.
Scottish top-flight clubs' average revenue in 2009 was €16m, the League of Ireland €1.3m, Northern Ireland 0.7m and Wales 0.3m .
Clubs will be monitored if there are warning signs such as: recording a loss in any year; spending more than 70% of revenue on wages; having overdue football-related payments or tax debts; high level of debts.
As with a tax declaration, the onus is on the clubs to provide the correct information to UEFA and they will be subject to spot-checks and face sanctions if they do not do so.
National associations will initially grant the licences but UEFA will have spot-checks to make sure that the rules are being applied correctly.
which clubs will be in trouble then ? imo chelsea , united, man city for definite