Coming up with the down payment can be one of the biggest obstacles to homeownership. If you have a retirement account, you may be able to borrow from it to get those funds, but it's an area where you ought to proceed with caution.

All three major types of private retirement accounts - 401(k)s, IRAs and Roth IRAs - offer options for tapping into them without penalty in order to obtain money for buying a home. Some employer-sponsored pension plans also allow participants to borrow against them or make early withdrawals as well.

Before proceeding, you want to figure out just how much money you'll need and weigh the merits of buying a home versus allowing the money to continue to appreciate in your retirement account. Owning your home outright can be part of a good retirement strategy, but it's by no means the only thing to consider. A financial advisor can help you sort through the pros and cons.

401(k) plans

Of the private accounts, a 401(k) offers the ability to obtain money now while still keeping your retirement planning on track. You can borrow up to $50,000 from your account, providing that you don't exceed half your account balance, and pay it back over time, with interest.

The great thing about this approach is that the interest you pay goes back into your account - you're basically paying yourself. So your retirement account continues to grow on schedule. Most loans from 401(k) accounts have to be repaid within five years, although some will allow as long as 15.

On the downside, with this approach you not only have to budget for your mortgage payment, but for paying back the loan to your 401(k) as well. Also, the interest you pay on a 401(k) self-loan is not tax deductible, unlike mortgage interest.

The biggest downside with a 401(k) loan is that if you quit or lose your job, you have to repay the entire amount within 60 to 90 days - otherwise, it's considered a distribution and you'll have to pay a 10 percent penalty, in addition to being subject to income taxes.

Roth IRA

With a Roth IRA, you can withdraw up to $10,000 penalty free for the purchase, repair or remodeling of a first home, provided you've had the account for at least five years. You don't have to pay taxes on the withdrawal but you do have to use it within 120 days to avoid the early withdrawal penalty if you're younger than age 59 ½.

The "first home" requirement is a bit of a misnomer, by the way - it only means that you can't have owned another home within the past two years.

In addition, you can withdraw any amount up to the total of your contributions to the account at any age, without penalty or taxes. It's only when you withdraw the earnings from a Roth IRA prior to age 59 ½ that the penalty and taxes kick in.

Traditional IRA and pensions

If you have a traditional IRA, you can withdraw up to $10,000 penalty free for the purchase, repair or remodeling of a "first home," same as with a Roth. The difference here is that you'll have to pay taxes on the amount taken out.

Of course, neither a traditional or Roth IRA include a provision for automatically repaying the amount withdrawn back into your account. So unless you accelerate your contributions in order to catch up (and which you won't be able to do if you're already contributing the maximum each year), taking money out of either type of IRA for a down payment will mean a permanent dent in your retirement account.

Finally, some employers that still offer pension plans that allow qualified employees to take early withdrawals or borrow against their accounts. Of course, this will vary among different employers and pension plans, so there's not much specific information that can be provided here. If you're interested in going this route, the best way to proceed is to contact your pension plan administrator to learn what the rules and procedures are.