A personal exemption is added to your tax return automatically, as long as you don't indicate that someone else is claiming you as a dependent. You don't list yourself as a dependent of yourself. Also, a spouse is not a dependent.
You can see whether you claimed a personal exemption by looking at line 42 of your 1040:
- My Account
- View Tax Summary
- Preview 1040
- Line 42: personal exemption of $4,050 ($8100 if married)
Claiming 0 allowances on your W4 is a totally different issue. That simply relates to withholding. Sometimes people claim 0 to have more taxes withheld.
You get an exemption for yourself and each person listed on your return. Each exemption is $4,050
1040 line 42
1040A line 26
Or for a 1040EZ the 4,050 is included on line 5 with the 6,300 standard deduction.
So for Single line 5 would be 4,050+6,300 = 10,350
For Married line 5 would be 8,100+12,300 = 20,700