Extra cash - go towards mortgage, or stock?
It's six of one a half dozen of another.   Investing the cash is a little more risky.  You know exactly what you'll get by paying down your mortgage.  If you have a solid emergency fund it's probably most advisable to pay down your mortgage.   If your mortgage is 3% and your investment makes 3.5% you're talking about a taxable gain of 0.5% on the additional cash.  Is that worth it to you? Sure, the S&P has been on a tear but remember, past results are not a guarantee of future performance. the math makes sense to invest instead of paying down, but... how much would you borrow at 3.5%, to invest the money into the stock market? It's the same question, just turned around.
The best thing for you to do will be to start using the Cash Flow report instead of the Income and Expense report. Go to Reports -> Income and Expense -> Cash Flow Once the report is open, open the edit window and open the Accounts tab.  There, choose your various cash accounts (checking, saving, etc.).  In the General tab, choose the reporting period.  (And then save the report settings so you don't need to go hunting for your cash accounts each time.) GnuCash will display for you all the inflows and outflows of money, which appears to be what you really want. Though GnuCash doesn't present the Cash Flow in a way that matches United States accounting rules (with sections for operating, investing, and financial cash flows separated), it is certainly fine for your personal use. If you want the total payment to show up as one line on the Cash Flow report, you will need to book the accrual of interest and the payment to the mortgage bank as two separate entries. Normal entry for mortgage payments (which shows up as a line for mortgage and a line for interest on your Cash Flow): Pair of entries to make full mortgage payment show up as one line on Cash Flow: Entry #1:  Interest accrual Entry #2:  Full mortgage payment (Tested in GnuCash 2.6.1) Based on your numbers, it sounds like you've got 12 years left in the private student loan, which just seems to be an annoyance to me.  You have the cash to pay it off, but that may not be the optimal solution. You've got $85k in cash!  That's way too much. So your options are:  -Invest 40k -Pay 2.25% loan off -Prepay mortgage 40k Play around with this link: mortgage calculator Paying the student loan, and applying the $315 to the monthly mortgage reduces your mortgage by 8 years. It also reduces the nag factor of the student loan. Prepaying the mortgage (one time) reduces it by 6 years. (But, that reduces the total cost of the mortgage over it's lifetime the most) Prepaying the mortgage and re-amortizing it over thirty years (at the same rate) reduces your mortgage payment by $210, which you could apply to the student loan, but you'd need to come up with an extra $105 a month. "But in the debt-payoff-first scenario, I'd be wiping out my debt in   two years. It would take several more years if I were to just pay the   minimums and put the extra money toward investing instead. Right. The idea is that in 2 years, you are likely to have more in the savings/stock account than you owe on the loan. But. The range of returns for X years has a smaller standard deviation the greater X is. e.g. any year has about a 1 in 3 chance of being negative. A 10 year period had a negative return (-1% CAGR) in the '00s recently, but the 15 year return even around that decade would have been successful. Jan 1 '96 - Dec 31 2010 returned 6.76% CAGR, Jan 1 2001 - Dec 31 2015 returned 4.96% CAGR.  This tells you that the time frame is as important as your sleep factor. Your 2 years? I'd just kill the loans. A 10-15 year horizon? I'd ask how you ""feel"" about that debt. The cost of going after a potential higher return may not be worth the risk to many. For some, it's fine. I retired, with a mortgage still in place, but the money in my 401(k) that could have paid off the mortgage is now about twice the remaining balance. So I sleep like a baby.  In the end, I'm a fan of investing for the long term vs paying off low rate debt, but it's a choice based on the individual." The tight lending standards such as elimination of low-documentation and sub-prime mortgages and requirements for lower loan to value, contribute to keeping all but those with pristine credit and cash reserves out of the market.  Some might consider this good for long term stability in the market.    I just went through doing a 20% down mortgage plus had to have one year extra liquidity in reserve. Simply put, the interest you're paying on your loans is eating into any gains you have in the stock market.  So, figure out how much you're paying in interest and consider the feasibility of paying off some of the loan.  Also figure in if you would be selling the stock at a profit or a loss.   Generally speaking, a home loan is typically long-term, with a high principal.  I believe the consensus is that it is typically not worth paying down extra on it.  A car loan, though, is much shorter term, with a lower principal.  It may be worth it to pay that down. I would certainly consider paying down the loan with 10% interest, even without running any numbers. What about doing this without selling stock?  The reason I suggest that is that you should not sell the stock unless you truly need the money or for some material reason(s) related to the company, the market, etc.  (Of course, one other reason would be to cut losses.) Unless I was looking to sell some stock anyway, I would try other ways to come up with the money to pay down the highest interest loan, at least.  If you are thinking of selling stock to pay down debt, definitely run the numbers. "Your first question has been answered quite well already. To answer your second question: ""If you pay extra, do you want the extra to go toward the interest or   toward the principal?"" This gives the consumer some flexibility to decide how additional payments are applied. It might seem like a no-brainer to always apply extra payments towards principal - that way, the interest amounts on future payments will be lower and (if you're billed a fixed amount each month) more of each regular payment will then be applied to principal, shortening the term of the loan. However, while it would mean spending more over the life of the loan, there are certain advantages to applying extra payments towards interest†. The main advantage is that it pays your account ahead and means you don't have to make another payment as soon. You could use this strategy to give yourself a buffer of several months, so that if you should ever run into financial hardship you can stop making mortgage payments for a while without the risk of foreclosure. † Note, in most cases it's more likely that you are simply paying more without specifying to the lender that it should be used as principal curtailment. I haven't seen cases where you can explicitly ask the extra to be ""applied toward interest"". In this situation the funds would be held until you've provided enough to cover one or more monthly payments in full, at which point your ""next payment due"" date will simply be extended.  Another advantage is that the funds that are being held (not due yet, not allocated toward any specific payment, maybe held in escrow) may be refundable to you, upon request. This would depend on the lender's policy. Some will permit refunds of credit balances that go beyond what is necessary to cover the current month's bill. Whether you apply extra payments towards principal or not, it makes little difference to the bank. Any additional payments received increase their immediate cash flow. The cash can be reinvested immediately by them into whatever they are currently focusing on." Depending on your bank you may receive an ACH discount for doing automatic withdrawals from a deposit account at that bank. Now, this depends on your bank and you need to do independent research on that topic. As far as dictating what your extra money goes towards each month (early payments, principal payments, interest payments) you need to discuss that with your bank. I'm sure it's not too difficult to find. In my experience most banks, so long as you didn't sign a contract on your mortgage where you're penalized for sending additional money, will apply extra money toward early payments, and not principal. I would suggest calling them. I know for my student loans I have to send a detailed list of my loans and in what order I want my extra payments toward each, otherwise it will be considered an early payment, or it will be spread evenly among them all. Leverage is when you borrow in order to invest. Mind you, most people aren't going to just give you money to gamble on the stock market completely unsecured; rather, you deposit (say) $10,000 and buy a stock... and then you have $10k in assets which you can borrow against, so you can buy another $10,000 of that stock. Now if the stock goes up you'll make twice the gain (2x leverage). However, if it goes down, you'll lose twice as much as well. If the value of your stock falls, your line of credit will be reduced as well; in this case, since you used all your credit and are now over your limit, your broker will issue a margin call (they will demand a deposit of additional funds, or they will sell some of your stock at their discretion). This protects you from owing more than you invested, but it's still sometimes possible (for instance, if a company spontaneously goes bankrupt and becomes worthless, and your stock becomes worthless). There are also things like leveraged index funds and commodity funds which aim to return some multiple of the market's earnings. These are designed for intraday trading, though, and usually end up underperforming significantly over the long term. [edit] Mose people who accept borrowed funds should generally accept real cash as well. However, if you're trying to short sell, i.e. borrow shares and sell them (in the hopes you can get them back cheaper later after the stock falls) you will need a margin line of credit to do so as well. [edit 2] clarified margin calls