Give a Haltom City woman credit for taking the time to do something that few do. She worked to understand the intricacies of her credit card bill.

All Hao Tran wanted to know was this: Does the issuer of her AT&T Universal Card apply any payments she makes above the monthly minimum to the higher interest rate charges on her card rather than the ones at a lower rate?

A federal credit card law, now a year old, requires credit card companies to permit customers to pay off charges with higher interest rates first.

For credit card users with one interest rate, this wouldn't apply. But some statements show multiple annual percentage rates. If, for instance, someone made a purchase, transferred a balance and took a cash advance, there could be three interest rates on the same monthly statement.

Tran gave me seven months of her credit card bills. For each, using pencil and paper, she tried to calculate how her payments were being applied. She suspected that it was not done in compliance with federal law.

Her case points to the next round of debate in the battle between consumer advocates and credit card issuers. Recently, the organizer of the new U.S. Consumer Financial Protection Bureau promised that making credit card agreements and terms easier to understand is a top priority.

I couldn't decipher Tran's bills, either. So with her permission, I took them to credit card expert Bill Hardekopf, who operates LowCards.com, a website that helps consumers understand what's happening in the volatile credit card industry.

"How do you understand these bills?" he asked. "Certainly, this needs to be cleaned up by the issuer. This is very difficult to read."

AT&T Universal Card is owned by Citibank. Citibank declined to answer my questions about how it presents its bills to customers. Citigroup spokesman Sean Kevelighan told me that Tran's payments are being applied in accordance with federal law.

"After a customer has satisfied the required minimum payment, any amount over that will be allocated towards the higher APR [annual percentage rate]."

That's all Citi would say.

Elizabeth Warren, the special adviser in charge of organizing the new federal bureau, jolted the credit card industry last month when she signaled in an interview with The Associated Press that the reform law was only the first step.

"Think about how long a credit card agreement has become," she said. "It's become pages and pages and pages of largely incomprehensible fine print. In effect, it's paperwork that says, 'Don't read me.' And that's a real problem. Because hiding in that fine print can be anything.

"So one of the things we want to push toward is trying to clear out that kind of shrubbery. So that if there are real changes that a company is proposing, they stand out. They're not camouflaged by all those other words."

She added, "You can't expect consumers to make good financial decisions, if they can't see the basic information."

That's Tran's problem. Last week, Tran received a letter from the office of Citibank's president stating that once the new law took effect, any debt she owes at a 24 percent rate would be paid before her remaining debt at 5 percent. No other information was provided.

Tran says she is still confused. Citi refuses to go into detail with her or me about whether Tran's pencil-and-paper computations are correct. The Watchdog wishes someone at the company would take the time to compose a more detailed response showing the customer how her payments are being applied. But it doesn't have to end there.

Here's The Watchdog's suggestion: The Federal Reserve Board regulates credit card issuers such as Citi. If Tran files a complaint with the Fed, government investigators will ask to see her records and will determine whether her payments are being properly applied.

Tran can also write to the Consumer Financial Protection Bureau detailing her concerns. The bureau's new website asks for consumer comments.

If enough people complain, that may counter bank lobbyists' pressure on lawmakers and regulators.

The Watchdog column appears Fridays and Sundays.

Dave Lieber, 817-390-7043

Twitter @DaveLieber