What specifically are you referring to? Are you referring to a distribution from a 401K or IRA? Are you under age 59 1/2? What is your other income and filing status?

Talking about a 457 tax deferd drop plan account. taking one time payment  of 500.000 

my income this year would go from 33.000 to83.000 they take automatic 20% for one time should I have them 

take more than 20% so I don't own more in tax like add an extra 9%?

If you are filing Married Filing Jointly, most of it would be taxed at 12%. If filing single or MFS, most of it would be taxed at 22%. 20% should be adequate unless you are subject to the 10% early withdrawal penalty. Use the TurboTax Taxcaster to help you decide: https://turbotax.intuit.com/tax-tools/calculators/taxcaster/