LTCG is exempt for an individual or HUF on sale of a residential house property, if such gains (not the whole consideration) is utilised to purchase or construct another residential house. It should be noted that the new house should be purchased within one year before or two years after the date of transfer. In case of construction, the new house should be constructed within three years from the date of transfer. Exemption will be limited to the capital gains or the cost of the new house, whichever is lower.
As per Finance Act,2014 the exemption is restricted to purchase of one residential house.
Although LTCG is required to be invested as per the timelines mentioned in Income Tax law (i.e. two/ three years from the date of transfer), it is possible that such investment may not be made before the due date of filing of return.
Accordingly, the unutilised amount of capital gain or net consideration can be deposited in a separate account maintained with a nationalised bank under the Capital Gain Account Scheme (CGAS). Such investment needs to be made before the due date of filing of return of income in order to claim exemption and should be utilised only for specified purposes within the stipulated time period. In case the amount deposited in CGAS is not utilised within the specified period, it shall be charged as LTCG of the year in which the time limit for making the requisite investment expires.
LTCG can be claimed as exempt in case the gains are invested in bonds of National Highways Authority of India and Rural Electrification Corporation within six months from the date of transfer. However, the exemption is limited to Rs 50 lakh in such a case. It has been recently clarified in the Finance Act 2014 that the limit of Rs 50 lakh is in aggregate and applies to total investment. The exemption up to Rs 50 lakh can be claimed only in one financial year, even if the specified period of six months covers two financial years
In your case, you cannot put amount in Bonds on your mothers name. Also you need to purchase a property with in due dates specified. Till then you need to stay invested in Capital Gains Account Scheme.