It depends on your other income if Social Security will be taxable. You should start by having some withholding then see how your tax return works out. Then you can change it to 0 or increase it for the next year.
Up to 85% of Social Security becomes taxable when all your other income plus 1/2 your social security, reaches:
Married Filing Jointly: $32,000
Single or head of household: $25,000
Married Filing Separately: 0