If Congress continues to do nothing for the next 12 days (including time out for a 7-day holiday) its members will get a $13,000 annual pay raise whether they like it or not. Feb. 16 is the magic day.

That's a rather negative way to put it, but sometimes in Washington the surest way to get something done is to do nothing.

Congress is, of course, doing lots of things. It is introducing bills, holding hearings, confirmation Carter appointees and issuing press releases. But it is not, so far doing anything positive (or negative) about the imminent pay raise for more than 20.000 career government executives, federal judges, political appointees and senators and representatives.

On Jan. 17, President Ford recommended substantial pay raise for top elected and appointed officials, most of whom haven't had more than one 5 per cent salary in half a dozen years. Ford said he supported the raises on condition that Congress adopt a strict financial code of ethies.

Committess have been formed to study that.And House Democrats on Wednesday bounced Rep. Robert L. F. Sikes (D-Fla.) from tne top job on a major military money subcommittee. Sikes was accused of seroius outside conflict-of-interest activities. Democratic caucus vote (189 to 93) is viewed, in part, as a gesture that the House is seroius about tightening up the outside financial actions of its members. Starting with Sikes.

By law, the pay raises Ford proposed will go into effect automatically on Feb. 16 unless either the Senate or the House vetes the plan. Those increases also would mean automatic raises fo from $29 a year to $7,900 a uear for top career federal officials. Many of them now earn the same *39,600 slalry although they have different grades and responsibilities.

The top career salary would go to $47,500 if Congress dosen't block the raises by the Feb. 16 deadline.

That time period is actually shorter than it seems because Congress will recess from Feb. 9 until the 16th, the last day it can veto the pay raises.

Despite the efforts of more than 30 House members to block the raises or to force a record vote on the pay issue, it appears that the House - with the blessings of the Carter administration - will stall any action until after the deadline.

On the Senate side, ays raise opponents except Sen. James B. Allen (D-Ala.) will find a parliamemtary who to bring the issue up for a vote. That would force each senator to go on record. The idea is to embarrass enough members to kill the increase.

Insiders now are betting that the raises will go through on schedule anyhow.