Neglecting to withdraw a required minimum distribution (RMD) from an IRA by the due date brings about a painful tax code penalty: 50%. Yes, you read that right. If you are supposed to withdraw at least $4,000 and (uh oh!) did not do as such, you have to write the IRS a check for $2,000. Keep in mind that on January 1, 2020, the RMD rules were modified.

Like many investors, you're likely aiming to build a comfortable nest egg to ensure a comfortable retirement. Among retirement financial planners, this is called the "accumulation phase." In this phase, your goal is to invest wisely by choosing stocks with long-term potential for your retirement portfolio, such as Fastenal (FAST Quick QuoteFAST - Free Report) , a current top ranked dividend stock.

But that's just half of retirement planning. The second part, the "distribution phase," sometimes gets overlooked even though it can be more fun to think about. That's because the distribution phase is where you determine how to spend your hard-earned assets.

Planning for the distribution phase is the time where you may make decisions about where you'll want to live in retirement, whether you'll want to travel, hobbies you may pursue, and other decisions that will affect your retirement spending.

Along with these aspects, it is important to consider the RMD that applies to most retirement accounts. Essentially, the IRS requires you to withdraw a specific sum from your qualified retirement accounts once you attain a certain age. That age used to be 70 1/2 but it is now 72.

What is the point of this mandatory withdrawal by the IRS? Not surprisingly, it's to be sure that the government gets their tax money. Without the RMD requirement, individuals could live off other income and never pay tax on retirement account gains. That cash could be left to family or friends as an inheritance and the IRS would not receive taxes from it.

The Most Important Things to Know About RMDs

Which types of accounts have RMDs? Qualified retirement accounts such as IRAs, 401(k)s, 457 plans, and other tax-deferred retirement savings plans like a TSP, 403(b), TSA, SEP, or SIMPLE IRA plan require withdrawals in retirement.

When do I have to start taking distributions? For most accounts, you must take your first distribution by April 1 of the year following the calendar year in which you reach age 72. If you retire after that age, you must take your first RMD from your 401(k), profit-sharing, 403(b), or other defined contribution plan by April 1 of the year following the calendar year in which you retire.

Every year after your start date, you are required to take your RMD by December 31. Remember, for Roth IRAs you do not have to take an RMD because you paid taxes before contributing. However, other types of Roth accounts do require RMDs, but you may be able to avoid them (for instance, by rolling your Roth 401(k) into your Roth IRA).

What happens if I don't take my RMD? The penalty for not taking a required minimum distribution, or not taking a large enough distribution, is a 50% tax on the amount not withdrawn in time.

How much cash do I need to withdraw? The RMD you are required to take is calculated by dividing your previous year's December 31st retirement account balance by a "distribution period" factor dependent on your age.

Here's an example to give you an idea of the math: Ann is 71 and will take her first RMD in the year following the year she turns 72. Her IRA balance toward the end of the preceding year was $100,000. Her "distribution period" factor is 27.4. Dividing $100,000 by 27.4 equals $3,649.63. This is the amount Ann is required to withdraw for her first RMD.

Learning about the "distribution phase" is just one aspect of preparing for your nest egg years.

To learn more about the tax implications of retirement spending - and much more about retirement planning - download our free guide: Retirement Made Easy.