Some Walmart customers and Sam's Club members across Alabama were incorrectly overcharged sales tax last week.

Effective Sept. 1, the sales tax rate on food decreased by one percentage point statewide. According to Joe Pennington, Walmart Press Office director, systems mistakenly charged both the old rate and the new rate at the time of sale.

"We're asking customers who used cash while shopping with us today to check their receipts. If they see they've been charged two separate sales tax amounts, bring that receipt to their Walmart store or Sam's Club and speak with a member of management to get a refund for the higher of the two taxes," Pennington wrote in a statement Friday. "Customers who used credit cards and other forms of payment will receive a notification their refunds were automatically applied."

Then later Friday, another statement was sent clarifying that while the initial announcement declared all store registers had been fixed, not all Alabama stores had addressed the issue. The company expected all stores to be fixed by that evening. A third statement confirmed that timeline.

Now, Walmart customers who shopped in Alabama on Friday, Sept. 1 are eligible for a $5 Walmart gift card.

To be eligible, customers need to bring their receipt dated Sept. 1 showing the overcharged sales tax to the customer service desk at any Alabama Walmart store. Gift cards will be available through Monday, Sept. 18.

"Sam's Club members impacted by the overcharged sales tax will receive $5 in Sam's Cash, automatically applied to their account," Pennington wrote.