One little tweet last December went viral and set off random acts of kindness nationwide. Brooklyn writer Ashley C. Ford tweeted, “A cool thing you can do today is try to find out which of your local schools have kids with overdue lunch accounts and pay them off.” That post was retweeted more than 10,000 times, was covered on the Today show, and raised more than $100,000 in donations for kids’ lunches.

But how can you actually go about donating to pay off a kid’s school lunch tab? The answer is different for every school district in the U.S., but SF Weekly reached out to the San Francisco and Oakland Unified School Districts to see how interested donors can help make sure Bay Area kids aren’t denied lunch for past-due accounts.

The districts will not make public the names of kids with overdue lunch accounts, for obvious privacy reasons. But they will accept general donations that go directly to paying off past-due accounts, and the past-due accounts really are a problem.

“We have approximately $330,000 annually in unpaid meal charges,” Oakland Unified School District’s Executive Director of Nutrition Services Jennifer Le Barre tells SF Weekly. “We anticipate this debt going up, especially with new minimum wage increases. For example, a family of four with two adults working full-time minimum wage no longer qualifies for the free or reduced-price meals.”

San Francisco Unified School District has an online donation page, which also offers a mailing address if you prefer to send a check instead. “In 2007, SFUSD’s Board of Education passed the ‘Feed Every Hungry Child’ resolution, which formalized the district’s commitment to ensuring students are not denied a school meal because of inability to pay,” the site notes. “Students who cannot pay are offered the same choices as all other students. However, a donation will help SFUSD to continue offering quality meals to all children as they come through our meal lines.”

For Oakland schools, you can donate by sending a check to OUSD Nutrition Services to the address 900 High Street, Oakland, CA 94601. “Since we feed all students regardless of the ability to pay, we are creating a specific account that will be used to reduce the debt at the end of the year,” OUSD’s Le Barre says.

Both unified school districts currently serve kids lunches, even if the students can’t pay. But that arrangement may not be able to last with reduced eligibility looming and the threat of steep cuts from the Trump administration. So your donation can still make sure that kids aren’t faced with the threat of going hungry during the school day.