John Puzey from Shelter Cymru told ITV News that more and more people are coming to the charity with concerns about how they can pay their rent.
He said "we are really concerned that people will try to cut back on other things - food, fuel etc - to try to pay that rent, but ultimately may fall into arrears."
Up to 1,500 families across Wales will be affected as benefit payments are capped at £500 per week from today.
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Alban Hawksworth, from the Welfare Benefits Specialist for charity 'Turn2us,' says up to 1,500 families through Wales will be effected by the changes.
Hundreds of benefit claimants across Wales will see their payments capped at £500 a week from today. New rules by the UK government mean families can no longer claim more - and single people will be limited to £350 a week.
Most will see a reduction in their housing allowance meaning they'll have to move or make-up the shortfall. The government says no-one should receive more in benefits than those working. The majority of those affected in Wales will be in Cardiff - where an estimated 300 people will see a cut.