That is correct, but the article should have used the verb "evade" rather than "avoid." Apparently if you don't have receipts to document your expenses, then whatever expense allowance you are paid by the state becomes wage income. Christie didn't have the receipts, either because he incurred no expenses (in which event what he did is flat out illegal), or if he did, does not have the receipts. If he can find or secure from vendors the receipts, than his tax problem to that extent is correctable.
I don't see how a CPA could have signed his tax return, assuming one did. If he told the CPA he had receipts, but lied to the CPA, then he is in real trouble, maybe criminal trouble.
Anyway, he's done. Even if, to be extremely generous and give him the benefit of the doubt, in a situation that looks really bad, he was just negligent, a guy who is negligent is not good POTUS material, obviously.
Christie's office now denies the article's tax treatment, claiming that the expense account is not required to be included in Christie's income. Christie's office claims that any yearly excess was returned to the state, despite the claims made in the article.
Also, just because no receipts were required to be provided to the legislature doesn't mean that no receipts were kept or that the Governor's office didn't have an official policy requiring receipts from its employees.
You'd think that if the expense account were to be included in income, the state would have been required to include it on Christie's W-2, no? If they didn't, it's hard to see how the IRS could come after Christie criminally, receipts or no receipts.