What happens to your ability to borrow money based on our joint finances?
Several factors are considered in loans as significant as a home mortgage.  I believe the most major factors are 1) Credit report, 2) Income, and 3) Employment status If you borrow jointly, all joint factors are included, not just the favorable ones.  Some wrinkles this can cause may include: Credit Report - The second person on the loan may have poor credit or no credit.  This can/will hurt your rate or even prevent them from being listed on the loan at all, which will also mean you can't include their income. In addition, there are future consequences: that any late payments, default, foreclosure, etc. will be listed on all borrower's reports. If you both have solid work history, great credit, and want to jointly own the home, then there shouldn't be any negatives.  If this is not the case, compare both cases (fully, not just rates, as some agents could sneakily say you can get the same rate either way but then not tell you closing costs in one scenario are higher), and pick the one that is best overall. This is just information from my recollection so make sure to verify and ask plenty of questions, don't go forward on assumptions. The bank will consider total of both parties income for the loan qualification. Provided both parties will be listed on the mortgage. It might be worth talking to a mortgage broker, even if you don't actually end up doing business with them. Upfront Mortgage Brokers explained Finding an upfront broker near you In a nutshell, upfront brokers disclose what they are paid for their services openly and transparently. Many brokers don't, and you can't be too careful. But a consultation should be free. An experienced broker can help you to navigate the pros and cons mentioned by the other responders. Personally, I would never do business with a broker who can't/won't show me a rate sheet on the day of the lock. That's my personal acid test. You might be surprised by what the broker has to say regarding your situation. That was my experience, anyway.
Are financial institutions less likely to lend me money because of my age Yes.  But they are especially unlikely to loan you money because you have little income.   or because they know I avoid interest by paying things off aggressively? This won't affect them.  But you might ask yourself how much credit history you have.  Credit history can include all of loans, credit cards, rent, utilities, etc.  You mention three loans.  But you don't mention rent or utilities.  You may simply not have much credit history, even if what you do have is good.   But again, the biggest thing that they will look at is your income history.  If you have a small income, then it doesn't matter what your payment history is.  They don't want to loan money to people who need money.  They want to loan money to people who don't need to borrow but are instead bringing a future purchase into the present.   The ideal recipient is someone who has a high income and spends it all every month.  Such a person is likely to borrow heavily but be able to keep up the payments.   Obsessing about your ability to borrow is probably the wrong approach.  Instead focus on how you can meet your goals without borrowing.  Eventually your ability to pay will catch up.  Then they'll offer you money.  Of course, you might not need it then.   Note that when I say little income, I'm talking about their perspective.  You may be fully on track and making decent money or even very good money for your age.  But they're looking for people who are mature in their careers and regularly bringing home large sums but who spend it faster than they can get it. There are a few reasons, particularly for businesses. The first is opportunity cost. That chunk of money they have could be used to get higher returns somewhere else. If they can borrow from a bank at low interest rates to finance their ongoing operations, they can use their cash to get a higher return somewhere else. The second is credit rating. For public companies, ratings companies give high emphasis to companies with large reserves. This strengthens their ability to pay back the loan should it become necessary. A good credit rating in turn let's the company borrow money at lower rates. When a company can borrow money at low rates, it circles back to the first point where they can now put their reserves to better use. The third is leverage. Companies can use the cash they have built up to leverage into a larger investment. Assuming the investment works out, it will pay for the cost of borrowing over time. For instance let's say I have $1 million to invest. I can pay all cash for a $1 million apartment building or I can leverage that into a $3 million building. Assuming I run it well, the tenants will pay for the cost of borrowing $2 million and at the end of the term I'll be left with my $3 million building. The prime rate is the interest rate banks use amongst themselves to lend money to each other only. It is used as the basis (sometimes) for what interest rate banks charge you.  The prime rate is based loosely on the Fed rate.  There is a committee that meets regularly to set this and other industry interest rates. http://en.wikipedia.org/wiki/Prime_rate I am not 100% positive the following is totally accurate The banks keep our deposits and pay us interest for doing so.  They are paying us interest because they take yours, mine and everybody elses deposits as a large lump sum and invest that money.  Sometimes as business loans, sometimes as mortgages and sometimes as credit card. The banks have a book of business that will be EXACTLY how much credit they have extended to everybody.  But they do not keep that amount of cash in the vaults, only some smaller percentage of that large amount.  When I use my credit card and they need to transfer money to amazon.com, if they don't happen to have enough cash that day, they will just borrow from another bank that does, and the interest rate they pay to do so is the prime rate.  Since they are paying interest on the money they borrow to pay the debt I charged because they told me my credit was worth so much (...???...) they charge me a little bit more than that. Hence your credit card or mortgage's APR being based on the prime rate. I THINK that is what they do  If I am wrong leave a comment and I will update, or the mods can. "Before you are married, I recommend keeping your finances separate.  However, once you are married, I recommend combining your finances completely. In my opinion, marriage works best when you work together as a team, a single unit.  You no longer have ""his money"" and ""her money,"" or ""his income"" and ""her income.""  Nor is there ""his debt"" and ""her debt.""  There is only ""our money,"" ""our income,"" ""our debt,"" and ""our budget.""   Indeed, if you are the one with less debt, isn't it in your household's best interest to help eliminate your spouse's debt as fast as possible?  If you are the one with more income/employment, how do you quantify the monetary value of the spouse who stays at home more and manages the household?  You can't, and it is best not to try.  Instead, pool together all income and expenses, and work together to meet common goals. To do this, open up a joint bank account and close your individual accounts. Meet on a regular basis to decide your household budget.  If you do that, it doesn't matter who is responsible for the mechanics of paying the bills or balancing the budget.  These tasks just get assigned to someone, just like any other household chore. Usually, one of you will be more financially minded than the other, and that person will take the lead in setting the budget, paying the bills, balancing the checkbook, etc.  However, it is important that both people are aware of what is going on and have access to the financial information.   In our house, I am the one who takes the lead on financial matters.  I pay the bills (out of our joint accounts) and set the monthly budget using YNAB software.  However, my wife has the ability to look at YNAB at any time to see the budget, and she can log into the bank website to see the transactions there as well.  No secrets. To be clear, we each have a small amount of cash/fun money that we can spend without worrying about checking in with the spouse on every little thing.  But this is a small percentage of our budget, and we talk to each other before spending any significant amount of money." "My wife and I maintain seperate accounts. We have the bills split between us so that certain bills are paid by one of us, and other bills by the other. This is not a perfect 50/50 split as we don't make the same amount of money, but comparable enough that neither feels like they're doing all the bills alone. Our investments are similar. That means we each have a pool of money that we can spend on toys or entertainment as we see fit without overspending. Once my bills are paid and my savings are paid for the month, if I want to go buy some DVDs and my wife wants to buy a new lens for the camera, we don't have to agree. We just use our own money and do it. For us that's led to minimal friction or arguments over what to spend money on, simply because we aren't using the same pool. Getting it work requires getting the split right AND having the mindset that the other person is just as entitled to spend their share of the money as you are to spend yours. It really helps to eliminate issues where she spent money that I expected to be able to spend before I could, which can happen in a joint account. (We have no joint accounts, only things like the mortgage are in both our names.) I've been told by more then one person that how we're doing it is ""wrong"", but it works a lot better for us then trying to combine finances ever did. I think it also helps that we're younger, and this seems far less common amongst older couples." I don't understand how that's relevant. If 10 people loan you money and I'm one of them, you shouldn't expect that I will agree for you to pay me less money just because the other 9 agreed to it.    I loaned you that money with the expectation that I would get 100% of it back.  Others may choose to adjust the terms of their loans, but it doesn't mean I have to. Ok but if there's no money and nobody willing to lend, how are those payments made?   It's fine and dandy to have the theoretical obligation and willingness, but I'm wondering what happens when there's simply no more capability to borrow more.  Edit: Funny you say that, I'm moving in! "By protected you mean what exactly? In the US, generally you'd get a promissory note signed by B saying ""B promises to repay A such and such amount on such and such terms"". In case of default you can sue in a court of law, and the promissory note will be the evidence for your case. In case of B declaring bankruptcy, you'd submit the promissory note to the bankruptcy court to get in line with all the other creditors. Similarly in all the rest of the world, you make a contract, you enforce the contract in courts."