Thousands of federal workers drive their own cars on company (U.S.) business, and most of them lose money on the deal in wear and tear, gasoline charges, etc. That is because they had been limited to a 20-cent-per-mile payment, which was fine back in the days of cheap gas, but no longer fills the bill.

The good news is that within the next 30 days Uncle Sam will up the mileage maximum to 25 cents. That doesn't mean employes will get the full amount. Odds are the actual payment will be raised to around 22.5 cents per mile. But workers can be paid up to 25 cents under a new law signed Sept. 10 by President Carter.

That bill was pushed heavily by the National Treasury Employes Union. Many of its members -- IRS agents, inspectors and the like -- drive their own cars on duty.

Higher payments won't apply to U.S. workers who elect to drive their own cars, in lieu of government cars. They will continue to get a lesser rate.

Also due for a boost is the government's daily expense account, the per diem payment. The same bill signed by Carter raises the standard per diem from $35 to $50 per day, and boosts the per diem for high-cost cities -- like Washington, Chicago, New York, San Francisco -- to $75 a day. Those new rates will also be adjusted next month.