President Carter's new Pay Advisory Committee is scheduled to hold its first meeting tomorrow since the AFL-CIO biennial convention, with hopes of moving slowly closer toward a resolution of remaining key pay issues.

Although the panel is expected to do little more formally than approve details of proposals it has okayed in principle before, sources say it is inching toward a consensus on an overall pay standard and a low-wage exemption. i

While panel sources aren't offering any promises, there's some talk that the 18-member body may be able to reach an agreement in another week or two and send Carter a full range of recommendations by mid-December.

To date, the panel has worked out formal proposals on two of four key issues on its agenda -- how to handle cost-of-living increases in so-called "tandem" contracts, and how to count step increases for government workers.

However, it's made only modest progress on the other two issues -- what should be the new overall wage standard to replace the previous 7 percent pay guideline, and how much can a low-skill worker earn and still be exempt?

Sources say the panel has been hampered on the low-wage exemption question because the White House privately negotiated an agreement with labor that unions say all but decided the issue before the pay panel even was created.

The low-wage exemption previously was $4 an hour, and labor had been trying to push that up to $4.40. But labor sources say the administration offered to hike that up to $5 an hour if unions agreed to an 8.5 percent overall pay guideline.

Sources say labor now contends it has a firm agreement and the panel now is having difficulty persuading union leaders to reopen the issue. As a result, the guideline issue and low-wage exemption appear to be linked.

The two issues the pay committee settled in previous committee meetings include:

It agreed to allow unions whose contracts historically have followed "in tandem" the patterns set by settlements in related industries to take cost-of-living increases in cases where these tandem settlements included COLAs.

It voted to allow government employes to take "step increases as they advance through grade without counting them against the pay guideline, as long as they remained in each step for the full time traditionally required.

The pay committee so far has met four times since it was established by the administration in late September. The panel is charged with drafting recommendations for handling pay settlements in late 1979 and 1980.

The 18-member committee, comprising representatives from business, labor and the general public, is headed by John J. Dunlop, former secretary of Labor and director of the Cost of Living Council during the 1971-73 controls.