The use of the money was agreed during a meeting on Tuesday (May 17).
Planning appeals can be costly to defend and even more costly to lose if a planning inspector awards costs.
Liberal Democrat leader Adrian Moss stressed the need to have ‘the highest level of support at appeal’.
The first appeal will be heard in June.
It involves an application for 100 homes on land south of Clappers Lane, Earnley, which was turned down last summer.
The second appeal relates to two major housing schemes totalling up to 200 homes on land north of the A259, Flat Farm, Main Road and land east of Broad Road.
The plans were refused in October and the appeal will be held in August.
No date has been set for the third appeal, which was called after plans for 25 homes in Birdham were refused in last August.
Councillors also agreed to take £56,600 from reserves to cover the cost of retaining temporary agency staff in the planning department as a number of vacancies had not been filled.
Susan Taylor, cabinet member for planning, told the meeting that there had been an increase in major planning applications since the easing of pandemic restrictions.
She added that they had become ‘more complex in terms of water neutrality and nitrate neutrality’ and it was ‘essential to have a full team of experienced officers’.