My 1099-R has an "M1" in box 7, but turbo tax will only allow one item in box 7, which item do I put in box 7 the M or the 1?

To add more that one code in box 7 of your 1099-R:

1. Login to your TurboTax account
2. Go to My info
3. Wages & Income
4. Select Edit/Add by IRA, 401(k), Pension Plan Withdrawals (1099-R)
5. Click on Edit or Review by the 1099-R Form that you need to edit
6. Go through the questions and when you get to the Distribution Info, go the box as shown below, and mark I have more than one value in Box 7.  
7. This will open another window for you to add the other code.  

I also dealing with the 2 codes in Box 7 "1M" (number one & letter M) for my 1099-R.

History behind this is that I had a 401k loan but I left my employment & the employer generated two 1099-R's - one for a Rollover (Box 7 code "G") & the 2nd one for the outstanding loan I had with codes "1M".

When I enter "M" there is no extra 10% penalty added to the Tax Due Box but after enter "1" in the second #7 box then the 10% penalty is added to the Tax Due Box.

This is the what Publication 1099-R Instructions say about this on their page 8 thru the top of page 9 for PLAN LOAN OFFSETS & it just mentions  to enter code "M". 

Page 9 of IRS 1099-R Instructions….

Plan loan offsets. If a participant's accrued benefit is reduced (offset) to repay a loan, the amount of the account balance that is offset against the loan is an actual distribution. Report it as you would any other actual distribution. Do not enter Code L in box 7. A qualified plan loan offset is a type of plan loan offset that meets certain requirements. In order to be a qualified plan loan offset, the loan, at the time of the offset, must be a loan in good standing and the offset must be solely by reason of (1) the termination of the qualified employer plan, or (2) the failure to meet the repayment terms because the employee had a severance from employment. Report a qualified plan loan offset as you would any other actual distribution. In addition, enter Code M in box 7

Thank you for your advice.

The 10% penalty would apply if the distribution was early, meaning it was before normal retirement age of 59 1/2. The instructions you mention may not mention the code 1 as a distribution may not be early, in which cases the penalty would not apply. If the distribution is early in your case, you should use the code "1".  @JY1040 

Thank You ThomasM125 for your information. I believe that the Payor should have ONLY coded box 7 with "M" since the taxpayer was separated from work & did have a payback contract with the employer to have payroll deductions for the loan payback. You are correct the "1" should only apply when the employee just flat out take an early distribution for no allowed exemption. Thanks again.