How do I chance my withholding status with OPM?

[hal7806]

I am federal retiree. is there a form I need to get and if so, how do I get it?

[KrisD]

You can use this link for information. 

https://www.opm.gov/retirement-services/my-annuity-and-benefits/federal-state-tax/

[VolvoGirl]

Give them a new W4P https://www.irs.gov/pub/irs-pdf/fw4p.pdf

Maybe you can change it directly on their website if you can log into your account there.