The Summit Group is all over the new Payroll Service Pack like auditors on an unsupported entry. Check out their look at the fix in Microsoft Dynamics GP US Payroll Version 10 Releases Service Pack for FICA changes and Tax Updates . (I would have said like fleas on a dog but I like dogs. As for auditors…well, I wouldn’t let one lick my hand.)
Microsoft Dynamics GP US Payroll Version 10 Releases Service Pack for FICA changes and Tax Updates » Summit Group Software Blog
Payroll & HRMicrosoft & the GP EcosystemInstall, Upgrade & Admin
Archived post from 2011. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.