I'm confused. You are there a year but have 10 years of pay/PRSI? I assume from another job. That would have no effect on your situation, although with the recent budget I think you do need 2 years PRSI to get jobseekers benefit.
It's a little unclear what your employer is doing.
Is the gross remaining the same, but he is reducing the PAYE payment to revenue? If that happens surely he is just transferring the tax liability to you? If you did a tax return for this year you would get a bill? Not sure about the legal status of this action.
Is the gross being reported as less to revenue to allow him to pay less tax, and in effect pay you under the table? Definitely illegal.
If you want to help the guy out and be legal, I think you would have to accept a reduced wage.
Ix.