Some taxpayers who filed their income returns early this year can expect a one-week delay in receiving refunds because the Internal Revenue Service is tweaking its computer system in a stepped-up effort to prevent refund fraud.

"As with the start of any tax season, there are system validations that occur requiring some fine-tuning of our systems," the IRS said in a statement. "As part of this, some taxpayers will receive refunds approximately one week later than initial projections they may have received."

The delay affects only taxpayers who filed returns before Jan. 26.

Some file early to get their refunds as quickly as possible and urgently need the money to pay bills. H&R Block and TurboTax have posted notices to their customers about the delay.

The IRS is conducting additional screening for fraud this year before issuing refunds, but the IRS said the extra level of protection shouldn't affect its initially projected refund schedule of 10 to 21 days for those who file electronically and select direct deposit.

"The vast majority of taxpayers can still continue to expect to receive their refunds in a timely fashion," the IRS said.

The IRS also reminds taxpayers many different factors affect the timing of a refund besides the additional screening for fraud. Taxpayers should make sure their Social Security number and/or taxpayer identification number is accurate along with their address and bank routing number for direct deposit. The best way to make sure your return is error-free is by filing electronically, according to the IRS.

Taxpayers who file online can get more information from the "where's my refund" section at IRS.gov.

For more information, go here.