I contributed both pre-tax and post-tax dollars to my Dependent Care FSA. Should only pre-tax dollars be reported in Box 10 of my W2, or should the full amount reflect?

[emuvenus]

The post tax dollars have already been added to Box 1 and are showing as taxable income.  

[BillM223]

Box 10 on your W-2 should report all the dollars your employer spent on dependent care services. This can include things like on-site day care.

So, if your post-tax dollars ended up getting spent by your employer for dependent care, then yes, they should be included in box 10.

***Notes***

The W-2 instructions for box 10 say, "Include the fair market value (FMV) of care in a daycare facility provided or sponsored by you for your employee and amounts paid or incurred for dependent care assistance in a section 125 (cafeteria) plan." 

Then, they go on, "Report all amounts paid or incurred (regardless of any employee forfeitures), including those in excess of the $5,000 exclusion".

Then, "This may include (a) the FMV of benefits provided in kind by the employer, (b) an amount paid directly to a daycare facility by the employer or reimbursed to the employee to subsidize the benefit, or (c) benefits from the pre-tax contributions made by the employee under a section 125 dependent care flexible spending account. Include any amounts over your plan’s exclusion in boxes 1, 3, and 5."

The underlines part explains the post-tax dollars added to boxes 1, 3, and 5.