Some federal agencies appear to be rushing money into the hands of employees who missed out on pay during the 16-day government shutdown.

The Social Security Administration said in a message to employees on Thursday that it will advance a portion of the back pay they are owed under a temporary spending deal that Congress and the White House approved earlier this week to end the operational slowdown.

The funds are scheduled to appear in workers’ accounts on Oct. 22 or Oct. 23, according to the SSA. The agency’s next regularly scheduled pay date is not until Oct. 25, meaning personnel will see relief a few days early.

“One of our most important startup activities is to ensure employees are paid as quickly as possible for retroactive salaries,” the  SSA said in its message.

The agency said it will advance only 65 percent of the amount owed to its workers for Oct. 1-5, which represents only the start of the shutdown. The remaining balance will appear in workers’ regularly scheduled checks on Oct. 25.

It is unclear whether other agencies will advance back pay to their employees. The Office of Personnel Management and the Office of Management and Budget did not immediately respond to requests for clarification.

OPM’s guidance on 2013 shutdown pay does not specify dates for providing back pay. However, it requires agencies to pay employees at their usual rates, including any premium wages they would have received for scheduled overtime and night work if the shutdown had never happened.

To connect with Josh Hicks, follow his Twitter feed or e-mail  josh.hicks@washpost.comFor more federal news, visit The Federal Eye, The Fed Page and Post Politics. E-mail with news tips and other suggestions.