Should I save or pay off debt? That has to be at the top of the most common questions I have received over the years. And the answer is solid: It depends! But only on one thing: if you do not have an emergency fund saved and stashed in a safe place — I'm talking at least $1,000 — you should save madly while you keep paying the minimums required on your burgeoning debt. Once you have an emergency fund in place, the answer to that question is clear.

Dear Mary: I have $13,000 in credit card debt. I have designed a plan in which I would pay the amount of interest charged to me on my last statement plus $930 each month. The way I figure it, by doing this I will have this debt paid off in 15 months. I am going to have to dip into my investment account to come up with that additional amount each month, but I can do that. I could also just pay off the whole amount from my investment account (it is not a tax-advantaged retirement account), but I don't prefer to do it that way. My investment account is at about $209,000, and I really don't want to go under the $200,000 mark. What is your suggestion? — Anonymous

Dear Anonymous: You didn't say the interest rate you are paying on that debt, so I am going to assume it's the current average rate of 17.55 APR. And you didn't say how your funds are invested, so I will assume you are invested in the stock market (some equity stock, some bonds).

Here are the facts:

—You owe the $13,000 regardless of anything that happens in your life or the world. And you owe it at a huge rate of 17.55 percent interest. That works out to $190 interest per month. My point is that this is a sure thing.

—The money in your investment account is at risk. It could grow. It could shrink. You could lose it all overnight. That's the nature of an investment as opposed to money in a savings account. It is not a sure thing.

Here is the principle I recommend you follow: There is no better investment than a repaid debt because it comes with a guaranteed return. It is always the wise thing to invest in your debt (but only to the point where you are not raiding your basic emergency fund to do so). Pay off that $13,000 debt now.

By investing in this debt, you will, in essence, be earning 17.55 percent on that $13,000 rather than paying it to the credit card company. Let me explain how that works:

If you keep paying on the debt, next month when you pay that credit card payment you will be paying $190 in interest to the bank. But if you pay it off in full this month, next month you do not have to pay that $190. You get to keep it. That money is now yours and is the 17.55 percent interest you are "earning" on the $13,000 you chose to invest in your debt.

Your investment account ebbs and flows due to current market conditions. Many believe the U.S. stock market is going to go through a major correction in the coming months or years (read: crash). We're being told we could see a 30-percent drop or more. Will that happen? Your guess is as good as mine.

If the worst happens (your investment account suffers a mighty blow), you will still owe $13,000 on your credit card account. The wise decision would be to pay that off now and reap the benefit of not having to pay 17.55 percent interest (or whatever your exact rate is) going forward.

Invest in your debt. It's a sure thing with a solid return.

Mary invites questions, comments and tips at [email protected], or c/o Everyday Cheapskate, 12340 Seal Beach Blvd., Suite B-416, Seal Beach, CA 90740. This column will answer questions of general interest, but letters cannot be answered individually. Mary Hunt is the founder of www.DebtProofLiving.com, a personal finance member website and the author of "Debt-Proof Living," released in 2014. To find out more about Mary and read her past columns, please visit the Creators Syndicate webpage at www.creators.com.