<prompt> Human: My mortgage payment is a very American 1,776 per month. I generally round this up to a full 2,000, and specifically designate the 224 extra as to be paid towards the principal.I read an article a few weeks ago that actually suggested this was improper, and that I should instead save up the 224 per month in a savings account for a year, and then just pay a lump 2,688 on top of my last months payment. It alleged that this paid down the principal more aggressively so that you could actually pay off the house sooner.A few questions: 1 - Im not sure I fully understand that. Wouldnt I want to be actively pushing down the principal each month since thats what the interest is accrued against? By waiting a whole year, its accruing more and more interest on the principal, no? Can someone help me break down the math as to why this is the better option, or is that article just wrong? The only other benefit it mentioned that makes sense is, in case you fall on hard times, that reserve could also help keep the mortgage paid while youre out of work, rather than having zilch during a period of unemployment.2 - Is even overpaying the mortgage a smart move for a house I dont intend to keep? This is our starter home. Right now, my fiancee and I are DINK. Once we have kids, well absolutely need to upgrade to a larger home that we might consider keeping. I foresee us selling this property in the next 5 years or so. So am I even doing myself any favors by overpaying a house that I wont even have for 30 years to enjoy getting out of mortgage payments sooner? Do I reap any rewards when I sell?3 - If the answer to 1 is, yeah, pay a lump sum annually instead of a little extra monthly, does the same apply to student loans? We overpay those a little each month, designated to the principal also, but if theres some basic loan repayment math that shows that were better off banking the extra for a year and making a lump sum extra payment, should we do that for student loans too?Thanks for any advice!!  <response>: Others handled your questions pretty reasonably.Here is the simplest way to answer your question about how to allocate your extra income:Which of your debts has the highest interest rate? Paying extra on this gets you a guaranteed return on investment of whatever that interest rate is, less any tax benefits you get for student loans or mortgage interest. Is that interest rate higher or lower than the average return of an investment that you are considering?Example 1: Mortgage 4.25 tax-deductible; student loans 6.80 tax-deductible; best investment option 7 average returnIn this situation, I would put everything toward student loans since its a 6.8 guarantee, where your best alternative investment is 7 average meaning theres a good likelihood youll lose.Example 2: Mortgage 3.75; student loans 4.10; investment 8 averageIn this case, Id probably make minimum payments and then invest in a taxable account. If youre only looking at debt repayment in your considerations, then just pay the highest-interest-rate debt. 