Another 300 jobs are expected to be shed from the Department of Environment.
Spending pressures could force the relocation of staff and offering of early retirement and voluntary redundancies, a consultation document from the department said.
Road safety grants are among programmes facing reduced spending. It has to save £15.4 million next year. A shortfall in planning income has also affected finances.
Some expenditure on environmental programmes such as the repatriation of illegally dumped waste to the Irish Republic and wider anti-flytipping measures will be postponed because £4 million a year has been removed from the department's budget instead of expected plastic bag tax receipts.
All government offices are under pressure to make savings over the 2011-2015 budgetary period following last autumn's Comprehensive Spending Review which cut the Northern Ireland grant from Westminster.
Tuesday's consultation document said: "We anticipate that the further reductions in expenditure anticipated in the Executive's Draft Budget will create a need to further reduce the number of posts within the department by some 150 jobs.
"When combined with the 150 posts still to be removed from the department, the overall requirement for workforce reductions within the department over the budget period will be some 300 posts, with most of these reductions happening over the next 12 to 18 months."
Planning Service, the Northern Ireland Environment Agency and grants for road safety are all to face cuts.
There will be a cessation of grants towards funding for the acquisition of listed buildings at risk and a suspension of a systematic second survey of buildings of historic and architectural interest.
There will be a reduction in proactive pollution prevention and there will also be a decrease in the value of local road safety grants as well as the amount available for road safety advertising.