Restaurants could be investigated following complaints some altered meals during the Eat Out to Help Out scheme.
The government initiative saw diners offered 50 per cent of their meals Monday to Wednesday every week in August if they opened to dine out.
It was announced by the Chancellor in his 'mini budget' in a bid to kickstart the hospitality industry following the UK-wide lockdown.
In the first three weeks of the special discount more than 64 million meals were bought and the success saw call for it to be extended into September.
However, HM Revenue and Customs (HMRC) has said it will assess eateries' payments from the government amid complaints from customers that some reduced portion sizes and increased menu prices, The Sun reports.
This is because participating restaurants are able to claim the money back from the government through an online service supported by HMRC - not leaving the businesses that have struggled during lockdown out of pocket.
Some also claimed that restaurants and bars offered 'stripped back set menus' to only 'the basics on days the scheme was in place.
An HMRC spokesperson said: "HMRC will risk-assess claims to protect against fraud, and will check claims and take appropriate action to withhold or recover payments found to be dishonest or inaccurate.
"Businesses are required to retain records to support Eat Out to Help Out claims. HMRC may compare claims to reported turnover and income in tax returns.
"You can report fraud to HMRC if you think an establishment is abusing the scheme."
The scheme came to an end on August 31 and the government said last week that 87,000 claims have been made by restaurants taking part in the scheme.
