My wife and I each have a Roth IRA that we contribute the $4000 every Jan for new year. The IRAs are in two index funds with T Rowe Price. My question is: Which method of contributing would be more beneficial:

A: Contribute equal amounts monthly to the IRAs (aka Dollar cost averaging)

B: Continue contributing a lump sum each Jan.

If B then should we:
1) Contribute from regular savings
2) Contribute monthly the year prior to a separate fund and transfer the lump sum in Jan.

C: None of the above

Thanks in advance for all the help!

Mike

The answer to the question depends on what the market does during the year. If it goes up and down and stays about the same, dollar cost averaging is better. If it goes progressively up, you do better to have all your money in at the beginning.
I've seen tables showing how it is better to put the money in at the beginning of the year vs on the last possible date.
On average, markets go up, so on average, you are better off doing just what you are doing. That doesn't mean that years won't exist where the reverse is true.
Best wishes, Chris

Re: Your question on when to invest

My suggestion would be to put it all in at once in January even if you have to tap other savings. The sooner you put the most you can into a tax deferred plan the better. Yes, the market may go down in the short term but who can time the market. This type of investing is truly long term so short terms ups and downs don't matter. The only exception to this might be if you wind up triggering taxable gain to get the money to put in, as in selling appreciated securities in a taxable account. Even there I think you're better off investing early.

Good luck