Liberal Democrat ex-cabinet minister Michael Moore is introducing a backbench bill to make it a legal requirement that at least 0.7% of Britain's GDP is devoted to helping poor countries, in line with a United Nations target.
The coalition government agreed to the amount last year, but the promised legislation has so-far failed to materialise.
The 0.7% pledge, in line with the UN target, has previously had the backing of all three major parties, but this is the first time it will be enshrined in UK law.
More top news
A mild day for most with plenty of misty low cloud.
Scotland will become the first part of the UK to ban smacking if the bill goes through.