No, a joint return does not break the refund down by "his and hers" refunds. When you file a joint return you combine all of your income and all of your credits, deductions, dependents, etc. The refund comes in both names. It is up to you as a married couple to share in whatever way works in your own marriage.
There’s nothing in the program that will tell you this, and it can be a very complicated question. For example, if two spouses earn the same amount of money at work, then one would assume that the taxes owed are also split equally. But if one spouse has very low withholding and the other spouse has a very high withholding, then the refund might belong mostly to the spouse with the higher withholding. Or the tax bill might belong to the spouse who had the lowest withholding.
If you are separating and decide to file jointly, it would be best to agree in advance how to split the refund or tax bill. An accountant could look at your specific situation and give a general estimate or your attorneys may negotiate something as part of your separation or divorce agreement.
here's one way pro's do it for their clients but it would require you to purchase the desktop software or open two new online accounts.
each person income is entered on their own return (married filing separate). couples have to decide how joint income and expenses are to be split.
anyway on the each of the separate returns there's a balance due or refund. on the joint return there is a net amount.
say the joint return shows a net refund of $1000 while on one separate return the tax due is $400 and the other shows a refund of $1300 net $900. again a decision. does the one keep the entire $1000 or should the one owing pay the other $300 . other approaches are also reasonable.