Once you open an account in a Forex Broker and start to trade (SELL or BUY), you are paying to broker as spread or commission for opening and closing each trade. This Spread or Commission is broker's incoming from your trades. For example, when you open a trade on EURUSD currency pairs and pay 2 pips as Spread, this 2 pips will be broker's income.
As you know most of leading brokers have partners who introduce traders to them. Once traders who are introduced By a partner, open an account and make trades, broker pays to its partner as commission from its incomings from the trades. In previous example 2 pips is broker's incoming, so broker pays a part of these 2 pips (like 1 pip) to its partner as commission.
We have already understood how brokers and their partner earn real cash from clients' trades in the forex industry. At this point we can explain what is Forex Rebates.
Partner pay some of thier earning commission to the client who make the trade. So at this cycle some of the amount that the trader has paid as spread will be returned to himself/hisself. This is what called "Forex Rebates" or "Forex Cash Back". In above example if partner incoming is 1 pip from your trade on EURUSD, Partner pays 70% of the amount to you as "Forex Rebates". In this example your Forex Rebate is $7.
You can have a quite Legal and 100% guaranteed income from your trades either win or lose.
Now assume you have traded 10 lots a week on EURUSD. So you will get 7×10$ that's meaning $70 Net profit in a week form your trades that your partner pays. The partner pays Rebate amount in different ways like Internal Transfer to broker account ( The partner in its account in the broker will transfer to your account in the broker), WireTransfer, Skrill, Neteller, WebMoney and etc. in three options Daily, Weekly or Monthly.