How the 20-4-10 automobile procuring rule works

When shopping for a automobile, whether or not new or used, consultants say {that a} particular framework generally is a nice place to begin to maintain prices down. 

The so-called “20-4-10” rule makes use of three parts that will help you decide if a automobile buy is inexpensive: the perfect down fee, the utmost advisable auto mortgage time period and the share of your revenue that consultants say ought to go to vehicle-related prices per thirty days.

Not solely does the framework provide help to keep inside your price range, however some points can even preserve you from turning into “underwater” or “the other way up” on a automobile, or owing extra on a automobile than what it is value.

Nevertheless, “there’s at all times wiggle room,” stated licensed monetary planner Chelsea Ransom-Cooper, co-founder and chief monetary planning officer of Zenith Wealth Companions in Philadelphia.

It may be troublesome to fulfill all parts of the rule: You may discover it difficult to give you a big down fee given excessive automobile costs, for instance, or want an extended mortgage time period to deliver down month-to-month funds.

However needless to say additional cash spent on a automobile fee can imply much less is left in your paycheck to deal with necessary saving and investing objectives, comparable to constructing an emergency fund or boosting your retirement contributions, consultants say.

“A automobile is a depreciating asset, so we need to be sure that we’re placing more cash towards appreciating property,” stated Ransom-Cooper, a member of CNBC’s Monetary Advisor Council.

The primary piece of the 20-4-10 framework recommends drivers make a down fee equal to at the least 20% of the automobile’s worth. 

Making a 20% down fee helps in quite a lot of methods. First, you are in the end reducing the quantity you borrow, due to this fact decreasing the month-to-month fee for the mortgage and lowering the curiosity you will pay over the lifetime of the mortgage, consultants say.

What’s extra, the down fee additionally “acts like a buffer” towards depreciation since you acquire fairness within the automobile, in accordance to Bankrate. Vehicles are depreciating property, which means they lose worth over time, a contributing issue to turning into underwater on a automobile mortgage.

“Placing down 20% on the entrance finish helps keep away from you ending up in that form of state of affairs,” stated CFP Lee Baker, the founder, proprietor and president of Claris Monetary Advisors in Atlanta.

The “4” within the framework stands for a four-year or 48-month auto mortgage. Whereas a shorter mortgage time period means you should have increased month-to-month funds, you find yourself paying off the automobile sooner with much less curiosity paid.

Nevertheless, it is common to see drivers take the wrong way. Lengthening the time period of an auto mortgage is without doubt one of the few methods to decrease month-to-month auto prices, Ivan Drury, director of insights at Edmunds, not too long ago informed CNBC.

Within the second quarter of 2025, 84-month auto loans comprised of 21.6% of recent auto loans, up from 19.2% the quarter prior, in keeping with Edmunds information supplied to CNBC.

If you have to give your self “extra respiration room,” finance the automobile for 5 years, however attempt to make the identical funds you’ll have made in a four-year mortgage, stated Baker, who can be a member of the CNBC Monetary Advisor Council.

“Even in case you have a five-year mortgage, if you happen to pay the automobile off in three and a half or 4 years, it shrinks the quantity of curiosity you are going to pay,” he stated.

The third part of the 20-4-10 rule signifies that you shouldn’t spend greater than 10% of your month-to-month revenue on vehicle-related prices, which should embrace your automobile fee, auto insurance coverage, upkeep and gas.

Ransom-Cooper stated it is necessary to keep away from going over that threshold and to attempt to preserve prices as little as potential.

For instance, if you happen to make $4,200 per thirty days after taxes and deductions, and calculate the ten% of that determine, you shouldn’t spend greater than $420 per thirty days on transportation prices, in accordance to LendingTree.

“Attempting to remain as tight to that quantity as potential is a useful solution to just remember to do not get caught underwater,” Ransom-Cooper stated.

In apply, it may be troublesome to execute. Households spent on common $13,174 on transportation prices in 2023, the second largest expenditure class after housing, in accordance to a 2024 report by the Division of Transportation. In that 12 months, transportation made up about 17% of complete expenditures.

“Of the transportation gadgets bought, the common family devotes most of its transportation price range to buying, working and sustaining personal automobiles,” in accordance to the report.

Use the 20-4-10 rule as a tenet to see how a lot you’ll be able to really afford, stated Ransom-Cooper.

If you happen to discover {that a} 20% down fee is just too excessive and the brand new automobile is extra a “nice-to-have,” think about buying the automobile within the subsequent 12 months or two, she stated. 

But when your automobile not too long ago broke down and also you really want a brand new automobile to go to work, think about paying a smaller down fee and reducing again on different areas in your life to make the brand new expense possible, comparable to decreasing discretionary spending, stated Ransom-Cooper.