Is keeping old credit cards and opening new credit cards with high limits and never using an ideal way to boost credit scores?
Problems with your plan (in no particular order) there is a limit, once they have decided that you have enough credit they won't offer any more. If the economy changes (like it did in 2008) they can reduce the limit on existing accounts. If you don't use them, they may decide to close them. Using existing cards will encourage the bank to increase the limit on that card. opening cards can make some lenders nervous. Having a new card close to when you are applying for a mortgage or a car loan can make them less likely to lend you the max. You have to decide: Are you trying to buildup your credit limit? or your credit score? I disagree with the reply.   Your both impressions are correct. -   Do not close old credit cards because they keep your credit rating high (fico score) -   Also low utilization that credit cards report to credit rating companies, improves your rating. Your plan will work to increase your total credit capacity (good for your credit score) and reduce your utilization (also good).  As mentioned, you will need to be careful to use these cards periodically or they will get closed, but it will work. The question is whether this will help you or not.  In addition to credit capacity and utilization, your credit score looks at things like These factors may hurt you as you continue to open accounts.  You can easily get to the stage where your score is not benefitting much from increased capacity and it is getting hurt a lot by pulls and low average age. BTW you are correct that closing accounts generally hurts your score.  It probably reduces average age, may reduce maximum age, reduces your capacity, and increases your utilization.
The biggest risk is Credit Utilization rate.  If you have a total of $10,000 in revolving credit (ie: credit card line) and you ever have more than 50% (or 33% to be conservative) on the card at any time then your credit score will be negatively impacted. This will be a negative impact even if you charge it on day one and pay it off in full on day 2.  Doesn't make much sense but credit companies are playing the averages:  on average they find that people who get close to maxing their credit limit are in some sort of financial trouble. You're better off to make small purchases each month, under $100, and pay them off right away.  That will build a better credit history - and score. Simply staying out of debt is not a good way of getting a good credit score.  My aged aunt has never had a credit card, loan or mortgage, has always paid cash or cheque for everything, never failed to pay her utility bills on time.  Her credit score is lousy because she has never had any debts to pay off so there is no credit history data for her.  To the credit checking agencies she barely exists.  To get a good score (UK) then get a few debts and pay them off on time. I have found that between the Discover card and a Visa/Master Card a person has everything covered. In my case the Discover card had the best deal (cash back) and the Visa/Master Card took care of those times a vendor didn't take Discover. One big Box store (Costco) did trip us up, so we did end up getting an American Express card. But Costco is dropping that requirement in 2016. One advantage of only having a few cards is that the increase in your total credit line will be split among fewer cards. In your question the highest  max limit on one card is $2500, what will you do if you have to take a flight at the last minute and the Airline ticket is more than that? If you need a higher limit, ask for one of your existing cards to raise it; don't go out and get another card. If you see that one of the companies that you already have a card with has a better card, you can ask them to convert your account to that better card.  Yes higher total limit does help your utilization ratio portion of the score. But there is some opinion that they also look at the utilization ratio per card. So hitting one card to nearly the max can hurt your score. Three caveats about the number of cards: The only drawback is if you spend more than you can with the new limit and end up having to pay interest if you can't pay the balance in full. Other than that, there are no drawbacks to getting a credit increase.  On the flip side, it's actually good for you. It shows that the banks trust you with more credit, and it also decreases your credit utilization ratio (assuming you spend the same). Credit scoring has changed recently and the answer to this question will have slightly changed. While most points made here are true: But now (as of July 2017) it is possible having a large available credit balance can negatively effect your credit score directly:  ... VantageScore will now mark a borrower negatively for having   excessively large credit card limits, on the theory that the person   could run up a high credit card debt quickly. Those who have prime   credit scores may be hurt the most, since they are most likely to have   multiple cards open. But those who like to play the credit card   rewards program points game could be affected as well. source "Your use of the term ""loan"" is confusing, what you're proposing is to open a new card and take advantage of the 0% APR by carrying a balance.  The effects to your credit history / score will be the following:" The whole point of a credit report and, by extension, a credit score, is to demonstrate (and judge) your ability to repay borrowed funds.  Everything stems from that goal; available credit, payment history, collections, etc all serve to demonstrate whether or not you personally are a good investment for lenders to pursue. Revolving credit balances are tricky because they are more complicated than fixed loans (for the rest of this answer, I'll just talk about credit cards, though it also applies to lines of credit such as overdraft protection for checking accounts, HELOCs, and other such products). Having a large available balance relative to your income means that at any time you could suddenly drown yourself in debt.  Having no credit cards means you don't have experience managing them (and personal finances are governed largely by behavior, meaning experience is invaluable).  Having credit cards but carrying a high balance means you know how to borrow money, but not pay it back.  Having credit cards but carrying no balance means you don't know how to borrow money (or you don't trust yourself to pay it back). Ideally, lenders will see a pattern of you borrowing a portion of the available credit, and then paying it down.  Generally that means utilizing up to 30% of your available credit.  Even if you maintain the balance in that range without paying it off completely, it at least shows that you have restraint, and are able to stop spending at a limit you personally set, rather than the limit the bank sets for you. So, to answer your question, 0% balance on your credit cards is bad because you might as well not have them.  Use it, pay it off, rinse and repeat, and it will demonstrate your ability to exercise self control as well as your ability to repay your debts. Credit Score is rather misleading, each provider of credit uses their own system to decide if they wish to lend to you.   They will also not tell you how the combine all the factoring together. Closing unused account is good, as it reduced the risk of identity theft and you have less paperwork to deal with. It looks good if a company that knows you will agrees to give you more credit, as clearly they think you are a good risk. Having more total credit allowed on account is bad, as you may use it and not be able to pay all your bills. Using all your credit is bad, as it looks like you are not in control. Using a “pay day lender” is VERY bad, as only people that are out of control do so. Credit cards should be used for short term credit paying them off in full most months, but it is OK to take advantage of some interest free credit. Would opening a second credit card contribute in any meaningful way to my credit mix or no, since it's the same type of credit? Yes, multiple lines of credit help your credit score, even if they are all credit cards. There are experts on both sides of this argument though. For example, Fico says that you shouldn't open a new credit card just for the credit boost, while NerdWallet cautiously recommends it. My recommendation is that if you're disciplined with your credit spending, it will help a little. If yes, is it worth it to take the hit to my average account age sooner rather than later by opening a new credit card? If you want to build up your number of credit lines, do so well before you need to use your credit to take out a loan. Not only will your credit score take a hit from the average age dropping, but you'll also have a hard pull on your credit report. As Fixed Point points out, though, you will see a larger improvement to your credit score by adding another type of credit, such as a home loan, to your credit mix. If you are already limited your credit utilization to 10%-30% then you probably won't be able to reach your goal by just adding a credit card. Closing the card will be fine. The consequences are related to your available credit and actual/potential utilization. If you have less total credit, any credit you actually use will be a greater percentage of your total credit, manipulating your score downwards more greatly. The next consequence will be related to the age of your credit history, which is an average of your credit lines. This seems negligible and also beneficial for you, since your credit history is so young to begin with. See the accepted answer for this question.  What effect will credit card churning for frequent flyer miles have on my credit score? This does not directly answer 'how often...' that you asked, but it states that the answerer opens 5-15 accounts per year.  So the answer to your question is, as often as you want, as long as you manage your account ages. The reason for this is that there are two factors in opening a new account that affect your credit card score.  One is average age of accounts. The other is credit inquiries.  That answerer, with FICO in high 700s, sees about a 5% swing based on new cards and closing old ones. You'll have to manage average age of accounts.  I assume this is done by keeping some older ones open to prop up the average, and by judiciously closing the churn accounts. Finally, if you choose to engage in churning, and you intend to apply for a large loan and want a good credit score, simply pause the account open/close part of the churn a couple of months ahead of time.  Your score should recover from the temporary hits of the inquiries.   The churning communities really do have how to guides which discuss the details of this.  Key phrase: credit card churning. This strategy will have long lasting effects since negative items can persist for many years, making financing a home difficult, the primary source of household credit. It is also very risky.  You can play hard, but then the creditor may choose you to be the one that they make an example out of by suing you for a judgement that allows them to empty your accounts and garnish your wages. If you have no record of late payments, or they are old and/or few, your credit score will quickly shoot up if you pay down to 10% of the balance, keep the cards, and maintain that balance rate. This strategy will have them begging you to take on more credit with offers of lower interest rates.  The less credit you take on, the more they'll throw at you, and when it comes time to purchase a home, more home can be bought because your interest rates will be lower. A credit balance can happen any time you have a store return, but paid the bill in full. It's no big deal. Why not just charge the next gas purchase or small grocery store purchase, to cycle it through?  Yes - unused cards can get canceled by the bank, and that can hurt your credit score. In the US anyway. I'm guessing it's the same system or similar in Canada. I think you are interpreting their recommended numbers incorrectly.  They are not suggesting that you get 13-21 credit cards, they are saying that your score could get 13-21 points higher based on having a large number of credit cards and loans. Unfortunately, the exact formula for calculating your credit score is not known, so its hard to directly answer the question.  But I wouldn't go opening 22+ credit cards just to get this part of the number higher! I've read multiple times that the way to rebuild the credit score is to get a credit card and then have some minor charges on it every month and have them paid in full every month. Old negative events age and this disciplined activity rebuild the score to some not to horrible levels. Now it's true that it's hard to get reasonably good credit cards when your credit score is poor. Yet it's not necessary to have a good credit card for this case - such things as large credit limit are not needed. All that's needed is a long grace period so that there's no interest between the moment a charge is done and a moment the bill is paid in full at the end of the month. Yes, the card may have rather high interest and rather low credit limit, but it doesn't really matter. I've read once on MSN Money that people are offered credit even while they're in the middle of bankruptcy, so it's not impossible to get a credit card in the described situation. Goes without saying that a lot of discipline will be needed to have all this implemented.