I agree with cerhob...don't charge them anything provided they are not spendthrifts and have a purpose in life for their savings. We did not charge our daughter board at all for the 5 years she stayed with us after highschool (3 years at Uni & p/t work, plus 2 years full time work+ p/t study). She was very prudent and a strong saver (even while working p/t she could still save). When she married she had saved $50,000 to add to her fiancees savings towards a house deposit. If we had charged board that would not have been possible. I would much rather see my children get a kickstart into the property market instead of paying board. Cheers