In general, the allocation won't make a difference in the final, total tax liability of the couple because the dependency exemption gives a $ 40 tax credit (non-refundable) and nothing else. (dinesentax.com)
According to a 2013 analysis by the Parliamentary Budget Officer, the size of the gap totals nearly 7 percent of total tax liability in the United Kingdom and 14.5 percent in the United States. (liberal.ca)
For IRS Form 1040EZ Transcripts: «Total Tax Liability TP Figures Per Computer» minus «Health Care: Individual Responsibility» (studentaid.ed.gov)