Assuming that the $10,000 that went to the 457(b) was elective deferral to the traditional account in the 457(b), the new tax person is correct and your old tax person is incorrect. The amount available to be contributed to IRAs is the sum of the amounts in box 1 of each of his Forms W-2, minus any amount that might be present in box 11. Presumably the sum of the box 1 amounts is $13,000, limiting the total IRA contributions to $13,000 (with no more than $7,000 being contributed by either spouse alone).
From IRS Pub 590-A:
The IRS treats as compensation any amount properly shown in box 1 (Wages, tips, other compensation) of Form W-2, Wage and Tax Statement, provided that amount is reduced by any amount properly shown in box 11 (Nonqualified plans).
