Does FIFO cost basis applies across multiple accounts?
You decide on a cost bases attribution yourself, per transaction (except for averaging for mutual funds, which if I remember correctly applies to all the positions). It is not a decision your broker makes. Broker only needs to know what you've decided to report it to the IRS on 1099, but if the broker reported wrong basis (because you didn't update your account settings properly, or for whatever else reason) you can always correct it on form 8949 (columns f/g). To sum up: My question came from misunderstanding what cost basis applies to. Now I get it that it applies to stocks as physical entities. Consider a chain of buys of 40 stock A with prices $1-$4-$10-$15 (qty 10 each time) then IRS wants to know exactly which stock I am selling. And when I transfer stocks to different account, that cost basis transfers with them. Cost basis is included in transfers, so that removes ambiguity which stock is being sold on the original account. In the example above, cost basis of 20 stocks moved to a new account would probably be $1 x 10 and $4 x 10, i.e. FIFO also applies to transfers.
As noted above but with sources An improvement materially adds to the value   of your home, considerably prolongs its useful   life, or adapts it to new uses. You must add the   cost of any improvements to the basis of your   home. You cannot deduct these costs. Source Page 11, Adjusted Basis, Improvements Second, A repair   keeps your home in an ordinary, efficient operating   condition. It does not add to the value of   your home or prolong its life. Repairs include repainting   your home inside or outside, fixing your   gutters or floors, fixing leaks or plastering, and   replacing broken window panes. You cannot   deduct repair costs and generally cannot add   them to the basis of your home. Source Page 12, Adjusted Basis, Repairs versus improvements Generally, an expense for repairing or maintaining   your rental property may be deducted if you   are not required to capitalize the expense.  You must capitalize any expense   you pay to improve your rental property.   An expense is for an improvement if it results in   a betterment to your property, restores your   property, or adapts your property to a new or   different use. Source Page 5, Repairs and Improvements  Good Luck, DJClayworth's response is generally correct. You wouldn't have to pay taxes on insurance benefits, since those are in fact bringing you whole to what you've lost. However, in some cases you do need to consider taxes. Specifically, if the insurance payout is higher than your cost basis in the lost property. While you may think that this never happens (why would the insurance company pay more than what it cost you?), it in fact quite frequently does. Specific example would be a car used in your business. If you used your car as part of your business and deducted car depreciation on your tax return - your cost basis was reduced by the depreciation. Getting a full car cost payout form insurance would in fact constitute taxable income to you for the difference between your cost basis (adjusted for the depreciation) and the payout. Another example would be collectibles. Say you bought a car 20 years ago at $5000, you maintained it well during the years (assume you spend another $5000 on repairs), and it is now insured at FMV of $50000. But, alas, it got destroyed by a mountain lion who climbed over the fence and pushed it over a cliff. You got a $50000 payout from your insurance company (because you insured it for full FMV coverage, as a collectible should be insured), of which $40000 will be taxable to you. There may be more specific cases where insurance payouts are (partially) taxable. However, as a general rule, they're not, as long as they're at or below your cost basis level. If your primary concern is a drop in your credit score, go to a mortgage broker instead of multiple banks and finance companies. Each time you ask a bank or financial institution for a loan, they do a hard pull on your credit rating which costs you a couple of points. Visit a dozen lenders and you'll lose 24 points. You will also be signalling to lenders that you're shopping for money. If you visit a mortgage broker he does a single hard pull on your credit score and offers your loan query to a dozen or more lenders, some of which you may not have even heard of. This costs you 2 points instead of 24. If you are only going to visit one financial institution or another specific one, the drop in credit score is the same couple of points. The above answer only applies if you make loan inquiries at multiple institutions. Using a different cost basis than your broker's reporting is NOT a problem. You need to keep your own records to account for this difference. Among the other many legitimate reasons to adjust your cost basis, the most popular is when you have two brokerage accounts and sell an asset in one then buy in another. This is called a Wash Sale and is not a taxable event for you. However from the perspective of each broker with their limited information you are making a transaction with tax implications and their reported 1099 will show as such. Links:  https://www.firstinvestors.com/docs/pdf/news/tax-qa-2012.pdf I don't understand the logic of converting a cost of funds of 4% to a monthly % and then subtracting that number from an annual one (the 1.5%).  Unfortunately without seeing the case I really can't help you...there was likely much you have left out from above. As stated above, the IRA accounts themselves are individual.  But if you want to simulate a joint account, the following actions would help: Make sure to setup each account with the other spouse as the beneficiary so that each account goes to any surviving spouse should the unexpected happen. Some brokers (I know TDA does this) allow you to grant access to your account to another login, so that effectively one spouse could make the invest decisions for all your accounts.  This is better than simply sharing your username and password, which is against many T&Cs.  If you do this in both directions, each spouse has access to all accounts. Your assumption, the need for two distinct accounts is correct.  Are you sure that the deposit was made to the same account? Since a 401(k) doesn't really have an account number, just your social security number, it may be they report it to you as though it were aggregated, but it's improper for it to be so. With respect (I mean this literally, I have the utmost respect) to littleadv's answer - the aggregation of the two accounts cannot be legitimate. If I wish to invest my Roth side into investments that grow far greater than the Traditional side, the mixing of accounts destroys this possibility. Something is either wrong, or misunderstood. I am not a tax professional, only an investment professional, so please take the following with a grain of salt and simply as informational guidance, not a personal recommendation or solicitation to buy/sell any security or as personal tax or investment advice. As Ross mentioned, you need to consult a tax advisor for a final answer concerning your friend's personal circumstances. In my experience advising hundreds of clients (and working directly with their tax advisors) the cost basis is used to calculate tax gain or loss on ordinary investments in the US. It appears to me that the Edward Jones description is correct. This has also been the case for me personally in the US with a variety of securities--stocks, options, futures, bonds, mutual funds, and exchange traded funds.  From the IRS: https://www.irs.gov/uac/about-form-1099b Form 1099-B, Proceeds From Broker and Barter Exchange Transactions A broker or barter exchange must file this form for each person: Edward Jones should be able to produce a 1099b documenting the gains/losses of any investments. If the 1099b document is confusing, they might have a gain/loss report that more clearly delineates proceeds, capital returns, dividends, and other items related to the purchase and sale of securities.