Montgomery County, visited by President Obama Thursday, is losing about $760,000 a day in income tax revenue because of the federal government shutdown, according to new calculations.

County Finance Director Joseph Beach said it is a “fairly conservative” estimate. It is based on Montgomery’s approximately 70,000 resident federal employees, and county taxes as a ratio of total state taxes collected. Maryland estimates a daily loss of $4.2 million in taxes.

It represents about 4 percent of the county’s total daily revenue.

The $760,000 comes with a couple of caveats. It doesn’t include residents who work for federal contractors, data that is “very difficult to get our hands around.” It also does not account for smaller revenue streams such as hotel-motel tax receipts, bus fares and parking fees.