The study, by property firm Knight Frank, says care homes benefit from their own use class, C2, meaning that developers of such schemes need not pay affordable housing contributions.
But it says specialist retirement housing by contrast falls in the same C3 use class as general housing, so developers "must make the development finance add up when the affordable housing requirements are added into the mix".
Under CIL regulations, local authorities have discretion to distinguish between any two uses that can be shown to be different, without reference to the Use Classes Order 1987.
However, the Knight Frank report says most local authorities tend not to differentiate between specialist accommodation for older people and general needs housing, choosing to apply the same CIL rates to both.
Figures compiled for Planning's CIL Watch bulletin show that only a handful of local authorities' levy schedules contain different charges for retirement housing compared to general housing. These authorities include Hertsmere, Winchester, Kingston-upon-Thames, Purbeck, Dacorum and Three Rivers.
Knight Frank's report recommends the introduction of a separate planning use class for retirement housing, "which may leave the way open for some reliefs or even waivers of CIL on a case-by-case basis, much like the schemes that fall under the C2 planning class.
"This would allow councils to differentiate in their CIL charging schedule between housing and retirement housing," the report says.
A spokesman for retirement housing developer McCarthy & Stone said retirement housing schemes can be penalised by CIL because they include communal space that is needed to provide care and support for older people.
Churchill Retirement Living planning director Andrew Burgess said a "steer from government" would be needed to increase the number of councils exempting retirement housing from CIL.