If you are concerned because you are seeing $12,700 on Line 40 of your Form 1040, rather than $13,000, $12,700 is the standard deduction amount for married filing a joint return for 2017.
The 2017 Standard Deduction amounts are as follows (Look at the screenshot below):
Single or Married Filing Separately $ 6,350
Married Filing Jointly or Qualifying Widow(er) 12,700
Head of Household 9,350
You can see your deductions on Line 40 of your Form 1040.