Retail giant Home Depot has been mistakenly charging customers seven per cent provincial sales tax on dozens of tax exempt items for the past year and a half, the company said Tuesday.

In a statement issued to CTV News, the company apologized to customers that may have been impacted by the error.

"We encourage customers to visit their local Home Depot store with their receipt to see if they are eligible for a refund on the PST that may have been incorrectly charged," Dan McAreavey, VP of Contract Services and Canada West Operations, wrote.

"We truly value our customers and their business."

The company says it has not benefitted financially from the error and that all PST collected from customers has been remitted to the B.C. government.

Related: Some PST-exempt items that Home Depot is charging tax on

Heating and plumbing contractor Dan Miller shops at the store upwards of four times a week. As a frequent customer, Miller estimates he could be owed up to $5,000 because of the error.

"[It's] very disappointing, especially at a big company like Home Depot…[they] should be on top of that," he said.

"I want to get my money back. That's a lot of money."

PST exempt items in B.C. include materials and equipment used to conserve energy.

Many of the items Miller frequently buys at the store, like insulation, caulking and Energy Star windows, are PST exempt – but he didn't know.

"Never noticed that, never looked at the bill," he said.

Home Depot said it has captured a significant portion of the PST exemptions and are now asking the government for clarification "on the more complex exemptions."

"The operational processes around tax compliance are being fully reviewed to prevent this from happening in the future," the company said in a statement.

B.C. Finance Minister Colin Hansen told CTV News audit investigators follow up on any claims where a taxpayer believes they have been mistakenly charged sales tax.

Hansen said those consumers are entitled to a refund.

"They can make an application to the ministry and we will reimburse any amounts over $10," he said.

Related: Provincial PST overpayment rebates

Some of the PST exemptions on energy efficient products will no longer be in effect once the Harmonized Sales Tax -- or HST -- takes effect July 1.

With a report from CTV British Columbia's Shannon Paterson