An electronic sign warns riders in Rosslyn as WMATA starts another SafeTrack phase, this time closing the Blue Line between Rosslyn and the Pentagon, in Arlington. (Bill O'Leary/The Washington Post)

Arlington County’s top administrator on Thursday proposed a ­2-cent hike in the property tax rate to pay for growing school enrollment and increased funding for Metro.

The proposed $1.2 billion budget, a 4.3 percent increase from this year’s, would raise $14.8 million for the county and boost the average residential property tax-and-fee bill to $8,613, a $308 increase.

County Manager Mark Schwartz said the 3 percent rise in property assessments this year will generate enough tax revenue to cover the county’s existing obligations and allow officials to shift money to pay for smaller initiatives without a tax hike.

But paying for the “clearly extraordinary needs” of Metro and the Arlington public school system will require more money. “I never like advocating for tax increases or tax-rate increases, but both of these are critical priorities,” Schwartz said in a briefing before meeting with the county board.

The property tax rate, now 99.1 cents per $100 of assessed value, was cut by half a cent last year, a change that was offset thanks to rising home prices.

While the average tax-and-fee bill (which includes personal property taxes, water and sewer service fee, refuse fee, storm water fees and residential utility taxes) has risen steadily over the years, the tax rate has remained below $1 since 2013.

Alexandria’s city manager proposed a tax-rate increase of 2.7 cents earlier this week. Fairfax County is not proposing a rate increase, although its manager said last week that he would need a 2.5-cent hike in the property tax rate to provide all the funding the school system was seeking.

Arlington’s highly rated public schools expect 1,045 new students in the fall. The school district is expected to ask for more funding as its board works through its budget, but Schwartz said his proposed $21.2 million increase, coupled with the school district’s $77.7 million in cash reserves, should give the system “sufficient resources to address their budget pressures over the near-term fiscal horizon.”

He also proposed allocating $3.7 million to the school system in one-time-only revenue.

Schwartz warned that Arlington and other jurisdictions will probably face additional requests in the future for supplemental funding for Metro, especially if the region continues to reject a dedicated revenue source for the transit system.

“If the board adopts what I’m recommending, I’m sure we’ll get through next year, but it won’t solve the fundamental problem,” Schwartz said.

Schwartz said he found room in the budget for other initiatives, including improving street and trail lighting; putting more money into paving roads; improving facilities and synthetic turf fields and acquiring land; and adding 13 public-safety positions — seven sheriff’s deputies, three emergency-call-center workers and three police patrol officers.

He also set aside money to help address the county’s 19.8 percent commercial vacancy rate, create an online business-permitting process, and set up customer service standards for residents who want to know, for example, when a sign will be replaced.

The county board now begins two months of work on the fiscal year 2018 budget, with multiple workshops planned and two public hearings, set for March 28 and March 30. The board is scheduled to adopt the final budget and tax rate April 22.

Correction: Earlier versions of this article incorrectly said Fairfax County was proposing a 2.5 cent increase in the property tax rate. The county manager is not proposing an increase. Also, due to incorrect information provided by Arlington County, the article said about 700 new students are expected to enroll in the fall. In fact, the school district expects 1,045 more students. The article has been corrected.