What is the difference between a check and a paycheck?
"A paycheck is simply a check for your salary.  It's just like a rent check, or a birthday check, or a grocery check...  I've had ""paychecks"" that were personal checks from the owner of the business, I've had ones that are printed in the office I worked in and signed right there, and I've had paychecks that are printed through a third party company and mailed to me (my favorite, of course, is to forgo the ""paycheck"" entirely and get direct deposit :) ).  Really, they're all just checks. Although that's a little disingenuous, because banks are often slightly more trusting of paychecks.  However, this has little to do with it being a ""paycheck,"" per se, and more to do with the fact that they see you getting the same check for (roughly) the same amount on a regular basis; having seen you get a paycheck for the same amount from the same company for the last 12 months, there is less risk of the check bouncing or being returned unpaid, so you can often get banks to waive their hold policy and just give you the money." There is little difference.  A paycheck is a type of check used to pay wages.  These days many people opt for direct deposit.  So, the term paycheck can also refer to the payment itself: 1: a check in payment of wages or salary 2: wages, salary http://www.merriam-webster.com/dictionary/paycheck
The deadline for contributing to a 401K is the last paycheck paid in December. That may not be the last pay period that ends in December. For example if the last pay period ends on Friday the 30th and you get paid on Thursday January 5th, that check is the first in the new year.  The US government has rules regarding how quickly the money needs to be sent to the 401K trustee. It is possible that the money may get there after the first of the year, but the important date for you is the date of the last paycheck in December. The company form to set the contribution rate (it could also be on a website) will have a deadline to determine if the rate makes the next check or the one after that. The form will also have a maximum amount as a percentage of the check. Some could allow up to 100% but yours might not. So how much you can put in with the last paycheck or two is up to company policy and your pay rate. The company forms or website will describe how the company match works. If you were try and put as much as possible into a few checks, it is possible to hit the $18,000 yearly limit in just a small part of the year. In some companies that would mean that you could miss out on company match money, because that would never be more than x% of each check. For example if you were to put $3,000 per check with a base pay of $5,000 every two weeks and if the maximum company match was 5%. After 6 checks you would be done: you would have put in $18,000 and the company would have put in $250 x 6 or $1,500. If you were to spread the money over all 26 checks you would still put in $18,000 but the company would have put in $6,500. Here are some typical differences between savings and checking accounts: Depending on your banks offerings and your personal goals, you would have to decide which factors matter to you. It's certainly possible that you may conclude there is no difference in your case. from what I learnt in au and limited to au banking system ( very much like other western countries), banks settle their transfers ( inter banks) 4pm afternoon. Those transactions are like everyday between accounts, person to person, person to vendor(not credit cards), vendors  to vendors( small businesses) etc. as for large transactions banks use check accounts( yes banks themselves have check account for each other). Check accounts are settled in three business days( ex public holidays). When large business deal with large business, they use debentures and corporate bonds which is a business IOU and using banks as mediate to settle. IOUs have up to 60 days settle periods.  Some complications unique to au banking system.  There are only 4 large banks in au and they and their subsidiaries own 99% of the assets collectively. What gets more interesting is large 4 banks owns each other. Each banks holds significant amount shares of other banks. They are like 4 brothers with different surnames. All of it is to minimise risk and share profit. The amount you contribute will reduce the taxable income for each paycheck, but it won't impact the level of your social security and medicare taxes. A 401(k) plan is a qualified deferred compensation plan in which an   employee can elect to have the employer contribute a portion of his or   her cash wages to the plan on a pretax basis. Generally, these   deferred wages (commonly referred to as elective contributions) are   not subject to income tax withholding at the time of deferral, and   they are not reflected on your Form 1040 (PDF) since they were not   included in the taxable wages on your Form W-2 (PDF). However, they   are included as wages subject to withholding for social security and   Medicare taxes. In addition, employers must report the elective   contributions as wages subject to federal unemployment taxes. You might be able to keep this up for more than 7 weeks if the company offers health, dental and vision insurance. Your contributions for these policies would need to be paid for before you contribute to the 401K. Of course these items are also pre-tax so they will keep the taxable amount at zero. If there was a non-pretax deduction on your pay check that would keep the check at zero, but there would be taxes owed. This might be union dues, but it can also be some life and disability insurance polices. Most stubs specify which deductions are pre-tax, and which are post-tax. Warning. If you get the company match some companies give you the maximum match for those 7 weeks, then zero for the rest of the year. Others will still credit you with a match at the end of the year saying if you should get the benefit. It is not required that they do this. Check the company documents. You could also contribute post-tax money, which is different than Roth 401K, for the rest of the year to keep the match going. Note: If you are turning 50 this year, or are already 50, then you can contribute an additional $5,500 When I moved banks.  I had my old bank cut a cashier's check.  It isn't a check you write. They write it and give it to you.  I then took the cashier's check to my new bank to deposit it. I doubt it has to do with the check though. Old people can be slow sometimes. I bet a younger person could write the check in a Reasonable amount of time. I lost my debt card a while back and needed groceries before I got my replacement it only added about a minute of transaction time for $200 in groceries which already takes a few minutes just to ring up. There are some people that still get an old-fashioned paycheck but for the most part if you are an employee at a company you get a paystub while the money is direct deposited into your accounts.  Paying for stuff at a store with a check is not very common.  Most people use credit cards for that purpose.  A significant percentage of the population still use checks for paying there regular bills through the mail.  Although the more internet savvy people will most likely use online bill pay from their bank so they don't have to mail checks.  Personally I have only written about 15 checks in 5 years.  Mostly to people and not to businesses setup for receiving bill payments electronically. The bottom line is to keep most of your money in accounts with no check privileges and to not give the account numbers for these accounts to anyone. Keep just enough in your checking account for the checks you are going to write.