It looked so odd: Two sets of homeowners in Howard County seemed to be getting property-tax credits that added to their bill, rather than subtracting.

When I stumbled upon them in a database of Howard property taxes that we'll (fingers crossed) have online for you all to search later this month, I stared blankly at the pair. It had to be a mistake, right?

Right. Howard County officials, investigating after I inquired, said the stealth tax labeled as a homestead credit was a miscalculation by the state Department of Assessment and Taxation that got by the county's finance department. Officials expect the property owners will have refunds in hand by mid-July.

The trouble started with bills issued last fall, several months after the initial bills for last tax year went out. Both sets of homeowners, a couple in Ellicott City and a couple in Jessup, had successfully appealed their property assessments and were due adjustments.

Here's where it gets a bit complicated.

The state assessment agency -- known as SDAT -- needed to send the county the new assessment information, complete with a calculation of the amount of assessed value to be left untaxed as a result of the homestead credit. (The credit essentially caps the tax increases homeowners can see in a year, so someone with a $300,000 assessment might only be taxed on, say, $200,000 of it.)

In these two cases, the credit should have been zero. Both assessments dropped so substantially that they fell below the level that had been taxed before, wiping out the homestead break. Instead, a state employee accidentally keyed in the difference between the previously taxed amount and the new amount in a way that made the credit -- well -- a reverse credit.

It's unclear whether the homeowners had any inkling they'd been overcharged -- I couldn't reach them. But records show their mortgage servicers handled their property-tax payments, so the homeowners were probably in the dark.

The Ellicott City couple is due $1,941 plus interest, said Kevin Enright, a spokesman for the county. The Jessup couple is due $741 plus interest.

"In addition, we are reviewing all other transactions from that time period," he said in an email. "We had experienced some difficulty last fall with these transactions as new staff was being trained at SDAT, and I believe we caught most of the errors prior to processing. This situation has improved since that time."

Renee Mierczak, supervisor of the state assessment agency's Howard County office, said the department's fairly new computer system can automatically fix this sort of mistake. But in these two cases, a clerk handled it manually "because that's the way we've been doing it for years," she said.

"It's just getting used to the capabilities of the system," Mierczak said, noting that the clerk is no longer going the manual route.

She said her office has already sent the county corrected assessment records so the refunds can be issued.

"As soon as we were notified by the county, we made the adjustments," she said.

Got a housing news tip or experience to share? (Or just want to tell me something?) Email me at jhopkins@baltsun.com.