Research shows that more than 100,000 people in Scotland are not applying for tax credits for which they are entitled.
Independent experts at the Scottish Parliament have calculated that they are missing out on a combined total of £428 million in benefits annually.
However, the estimate does not include pension credits, meaning the exact figure could be much higher.
This has led to calls for Scottish ministers to use new powers to ensure Scots receive this money.
Tax credits were introduced by Gordon Brown more than a decade ago and have been the preserve of Westminster. However, new powers being given to Holyrood following the 2014 independence referendum, mean Scottish ministers will have a say over benefits for the first time.
Scottish Labour has called on Scottish ministers to increase public awareness of unclaimed credits in the upcoming Social Security Bill.
Mark Griffin, Scottish Labour’s welfare spokesman, said: “Tax credits have lifted hundreds of thousands of children out of poverty and allow families across Scotland to aspire to more than just making it to the end of the month.
“Making sure, in law, that cash goes to the people who are entitled to it could make a huge difference.”
The Scottish Government said it was currently looking at options for the new Bill.
But it said that making sure people know and understand the support they are entitled to would be a key part of its strategy.
Scottish Social Security minister Jeane Freeman said she would develop policies based on dignity and respect “which will help remove the stigma attached to accessing benefits” which, she suggested, put some people off claiming their entitlements.
Last year SNP MP Dr Paul Monaghan suggested that benefits left unclaimed should be channelled to Scottish Government funds.
At the time Conservative ministers said they did not have a breakdown for how much went unclaimed in different parts of the UK.
Charity AgeUK estimates £5.5bn-worth of pension credit alone goes unclaimed UK-wide every year.