If your mother gives you money do you have to pay capital gains tax?

Capital Gain is when some valuable thing that you own (capital) increases in value. It is computed as the difference between the price you got when you sold it, minus the price that you paid when you bought it. That formula assumes that both the purchase and the sale were fair transactions in a free market.

If your mother gives you cash, that's either a gift (if she did it just because she loves you) or it's income (if you did something to earn it). If it's income, then you almost certainly would have to pay income tax (assuming that you live in a place that has income taxes). I don't know about gifts.