GED 2014 costs $120 (4 tests/$30 per test). Your voucher is worth up to $80. You can use all of it at once if you apply to take all four subject area tests at the same time.
If you take all four subject area tests at the same time, the cost to you for the full test is $40. If you schedule each test separately, you can use $20 from the voucher on each test. The cost to you for each individual test is $10.
The maximum amount you'll pay to take the GED 2014 the first time with a voucher is $40.
The voucher is valid for 120 days from the date it is issued.