I guess I don't understand what 'Net' is. Is it the cost of the government, so if I earn 20k on the open market, are given 20k and taxed 10k (I have 30k in my pocket, and the gov has spent 10k)?
Net here is the amount received by the individual in basic income, less the portion of their taxes going to pay for the basic income, assuming it is funded with a 50% flat tax. So yes, if you earn $20k, are given $20k, and are taxed (for the purposes of funding the BI) $10k, the net (direct) effect of the basic income program on your bottom line is $10k.
I don't see where you're getting that. Presuming the numbers haven't changed since you commented, it looks to me like taking away half of every dollar earned.