a house, with heat and light, council tax paid, food on the table, TV and internet provided, washing machine etc. £20 a week does not cover that.
Yeah £20 doesn't touch the sides, but how many of you are working for £100 a week? At the end of the day he is still legally a child, if he was in education you wouldn't take anything from him. If you are REALLY going to miss the CBA make him give you that per week.
I started working at 16 whilst still at school working sat and sun 6 hours each day for about £3.40ph as a hotel cleaner. Really tiring work for crap pay. Used to walk the 6 mile round trip. Why would my mum take money from me? I bought my own clothes/toiletries/majority of my food (mum didn't really cook much), travel etc.
I didn't need her ripping me off and or controlling my money by taking it off me to save to teach me about working life etc. I am now 22 been out of the house for 4 years and have 6k in savings. Share a nice flat with my boyfriend which costs us about £1400pm in rent and bills which we half, after travel of about £100pm month I have just less than half my wage left for me, so over £100pw. (In response to do you have £80 - £100 a week just to spend on treats for yourself ???) However I do have the luxury of just having me to pay for, not any offspring.
Basically OP if you think you son is mature enough to enjoy his money responsibly whilst saving then no, don't take any money. If you think he needs a reality check to wake him up to what life is going to be like after he leaves home then yes, take a token amount. He has his whole life to pay bills and worry about money, just let him enjoy his first job.