Question: how to determine what percentage of social security is taxable?
Answer: If your base income is between $25,000 and $34,000 for a single filer, or from $32,000 to $44,000 for a joint filer, then up to 50% of your Social Security benefits may be taxable. If your base income is more than $34,000 on a single return, or $44,000 on a joint return, up to 85% of your benefits may be taxable.