Starting in July of this year I will start drawing social security about 21,000 a year. How much more should I expect to have to pay in taxes next year?

It depends on whether you have other income items to report.

In general, if your only income is social security, then you probably will not have to file a tax return and the income is not taxable.

However, if you have other income items, then your social security can become taxable (in part) if you exceed base amounts for your filing status.

See link below for reference.

https://ttlc.intuit.com/questions/1899144-is-my-social-security-income-taxable