No, that's not right, Myrddin.
Individuals will pay for their benefits via sales tax payments, not by having their incomes taxed.
Benefits are determined by their employer reporting their wages.
Individuals pay tax (including FICA) via a sales tax, not an income tax.
Please, basic info including FAQ.
So, does that mean benefits will be granted or withheld based on reported wages? Can you say means testing? The current payroll tax collects FICA according to income level and returns benefits according the amounts paid into the system. There is an auditable record of social security payments made by an individual taxpayer. NRST has no guarantee that sufficient sales tax will be collected to cover claims. A frugal person with an exceptional income could easily show large earnings and still make minimal contributions.
If a tracking system (national id card, SSN or standardized driver's licenses) is devised to identify actual contributions by a given taxpayer, the same infrastructure might be abused by imposition of unequal taxation. Unless the legislation explicitly prohibits unequal taxation, the politicians will interpret that as tacit permission to "enhance" the NRST as they see fit. I think the HR 25 proposal has more holes than Swiss cheese.