The commission says 37 parties reported donations late
Political parties reported £8.1 million in donations between January and March of 2008, according to new Electoral Commission figures.
Labour received £3m in donations and the Conservatives £4.2m. The Liberal Democrats declared £470,000.
The figures show the main parties still in debt, Labour by £17.8m, the Tories by £12m and the Lib Dems by £1.1m.
Commission chief executive Peter Wardle said he was "disappointed" 37 parties had reported a donation late.
The Lib Dems declared £112,000 late, the Conservatives reported £74,000 late and Labour £52,000 late.
Mr Wardle said: "We are disappointed at the scale of late reporting this quarter.
"We have already written to the parties and they've given us assurances that they are taking steps to ensure more timely reporting in line with the requirements of the legislation.
"We continue to monitor the parties closely and expect to see significant improvements in future reporting.
"We have repeatedly made clear the need for the commission to have a more flexible and proportionate range of penalties which would help us to deal with this issue.
"We hope to see these in the government's White Paper on reform of party finance and expenditure."