I'm not finding a clear answer to this with my googling, so I'm asking the forum. The deadline for actually funding the individual 401K is tax filing deadline plus extension - that I'm clear on.
What I'm not clear on is whether I can file my tax return before funding the account. Tax return is finished - I've got $28K to go on the 2018 SoloK, which I should be able to do no later than the end of May. Have already made 2018 IRA and HSA contributions, so this is the only outstanding item on 2018 taxes.
What I'd like to do is file for an extension, then file my federal (getting $2K refund) and state taxes (owe $2300 to 2 states this year due to changing jobs and moving), then finish funding the SoloK for 2018. One of those states is Maryland, and the sooner I can file that return, the less I will owe due to them charging penalties / interest even for a first year filer such as myself.