David Cameron is to launch a major crackdown on abuse of the immigration system , including plans for tougher visa rules to weed out sham marriages.
In a keynote speech, the Prime Minister will call for relatives joining their families in the UK to be able to speak English and have enough cash to live on.
He will say the Government wants to prevent immigrants becoming a burden on the taxpayer, so is looking at discounting promises of financial support from family and friends when considering applications and forcing some applicants to pay financial bonds.
The Prime Minister will say: "Of course in the modern world where people travel and communicate more easily than ever before and where families have connections all across the globe people do want to move to different countries to be with loved ones. We all understand this human instinct.
"But we need to make sure - for their sake as well as ours - that those who come through this route are genuinely coming for family reasons, that they can speak English, and that they have the resources they need to live here and make a contribution here - not just to scrape by, or worse, to subsist on benefit.
"A sample of more than 500 family migration cases found that over 70% of UK-based sponsors had post-tax earnings of less than £20,000 a year. When the income level of the sponsor is this low, there is an obvious risk that the migrants and their family will become a significant burden on the welfare system and the taxpayer.
"So we have asked the Migration Advisory Committee to look at the case for increasing the minimum level for appropriate maintenance.
Mr Cameron wants to stop sham marriages by extending the time it takes for migrants to qualify for a spousal visa.
He will say: "Time and again, visa officers receive applications from spouses or partners sponsoring another spouse or partner soon after being granted settlement in the UK, suggesting that the original marriage or partnership was a sham simply designed to get them permanent residence here.
"We simply cannot sit back and allow the system to be abused in this way."