The Welsh Government is repaying €3.4m (£3m) of rural funding to the European Commission following a critical audit report.
Last June Audit Wales found grants worth £53m in the £744m Rural Development Programme were made without ministers ensuring value for money.
The government said it was "disappointing" but its record on minimising repayments was "one of the best in Europe".
Plaid Cymru called it a "scandal".
Audit Wales' report found projects were given money without others getting a chance to bid, and without officials making sufficient checks that they were worth the cash.
The Auditor General for Wales called for controls to be strengthened.
Officials at the Welsh Government later entered discussions with the EU over the issues the auditor highlighted.
It says those discussions led to the potential "disallowance" payments being reduced from €33.1m to €3.4m.
The information was obtained by North Wales Plaid Cymru Senedd member Llyr Gruffydd.
In a written answer to him, Rural Affairs Minister Lesley Griffiths said: "Discussions with the EU over the issue highlighted in Audit Wales's report are complete, with the amount of disallowance confirmed reduced from €33,140,551 to €3,412,104.
"Whilst any disallowance is disappointing, it is the reality in delivering CAP [Common Agricultural Policy] funds, as all member states receive disallowance on many different aspects of the CAP, and Wales' record in minimising disallowance is still one of the best in Europe."
Disallowance is the technical term used to describe fines from the European Commission.
The Welsh Government also said that three projects were re-tendered, following the auditor's report, and in all cases the contract were won by existing suppliers.
Mr Gruffydd said: "This is funding that's meant for projects in rural parts of Wales and it's down to the Welsh Government to administer the schemes fairly and correctly.
"This hasn't happened in a number of cases and, as a result, much-needed funding for Wales is being lost.
"It's not good enough that the minister claims that Wales has a good record of minimising disallowance. She should take responsibility for failures like this."
Nick Ramsay, finance spokesman for the Welsh Conservatives, said it was "concerning" that a "significant amount of money" had to be repaid by the Welsh Government.
"The public need to have confidence In Welsh Government spending.," he said.
"It's important that lessons are learned so that the mistakes that were made are not repeated."
The Welsh Government has also been penalised a further €790,000 (£706,000) as a result of separate audit work related to the 2014-2023 regional development programme.
What is the Welsh Government's position?
A Welsh Government spokesperson said: "Disallowance of some form is completely normal for member states and as the figures show our rate is over 10 times better than the European average.
"We have set out ambitious plans for the future of farming in Wales in our Agriculture (Wales) Bill.
"These plans show how we will continue to support farmers to produce food in a sustainable way whilst taking action to respond to the climate emergency and to help reverse the decline in biodiversity."