There are so many profitable games that we can play by using credit cards that I can't even keep track of them all. In my area, we have Stop & Shop who gives gas discount points for spending $$. It's 10 cents/gallon discount for each $100 in purchases. There are specials and bonuses that are not insignificant. Before I go on, the gas is with Shell. Now, Shell has their own system called fuel rewards. If you link your master card and your stop & shop card, they then give you 15 cents per gallon discount for every $100 spent at stop and shop. My card is a citi double cash where I get 2% cash back. This past week, stop & shop had a coupon in their mailed circular for 2X gas points with a minimum $50 purchase. Although they say one per household, I used mine and my wife used her father's code and both were accepted. So the rundown:
Buying at Stop & Shop....groceries that I would buy anyways. I bought $50 and my wife bought $50. Both with 2x coupons, so we get 20 cents off a gallon and since we spent $100 on the master card, $2 back from them. Shell sees $100 spent on the linked master card at stop and shop so gives us another 15 cents a gallon off. Shell always adds 5 cents a gallon off when you purchase with the fuel rewards card (it's just a member card, not a credit card). So now I go and buy gas. I could buy in cash and still get the 20 cent stop and shop plus 5 cents fuel rewards, for 25 cents off or with the credit card, I'll get 40 cents a gallon off and since I'm using a gas 3% reward card, another cc cash rebate. Gas is (let's say) $2.50 a gallon and I'm going to buy 20 gallons (the max that is allowed for the discounts).
Cash costs $2.50 minus 25 or $2.25 times 20 or $45.
Using my 3% back card and the linked stuff, $2.50 minus 40 or $2.10 times 20 or $42 and 3% back, which is $1.26.
Cash cost me $145 for the groceries and gas using all available discounts.
Credit cost me $142 with $3.26 cash back or $138.74.
Sounds all complicated, but all I actually did here was use my credit card instead of cash. $6.26 for doing absolutely nothing on this one silly set of 2 purchases.