My 2 cents:
Part of the reason you can do a higher bill rate with a higher work level is that the person knows what they're doing and can fly through a return. If you're a sole prop without employees, then you can't bill out at the partner rate, cause no partner does the data entry through to the sign-off, unless their customer knows they're paying a premium for it. So, I'd try to think of it as a rate for my time spent prepping that's at a more entry-level rate, a rate for my time reviewing that's a bit higher, and then figure the percentages and determine a rate from that. If you'd bill an entry-level person who enters the tax data at $100/hr, and you figure that's 80% of the time, and you'd bill a partner at $200/hr and that's 20% of the time, then as a sole prop, I'd say $100×0.80 + $200×0.20 = $120 = sole prop hourly rate. (It's been too long since I've done taxes for me to know what percentages would go to review and prep, but that's just to be an example.)
Also…if I went to someone who was new, and lower experience, I would expect an equivalently lower rate. I'd also be a little hesitant about paying them by the hour, since they might have to spend 10 hours looking up something that the guy down the street who is more experienced and charges more per hour could find in 10 minutes. So…they might be happy to pay $150 for their 30-minute return, but not to pay you $300/hr for their 30-minute return. Especially as a sole prop, I'd be much more a fan of pricing by the form or by the return, so that you can make your money without them knowing the hourly rate. At least in non-tax fields (my dad was a small business owner in a couple different industries much of my childhood), you can make a LOT more if you're charging by job than by hour…and as the new guy on the block, I'd imagine that by the job will go over a lot easier with your clients. They're not taking the risk of you being slow, and they're not seeing how much they're actually paying you. 🙂
P. S. This is referring to the tax prep piece and all covered services (for example, if you'll assist clients with audits for free). Things outside of that – extensive tax planning etc. – would need a different pricing structure, but I'd still try to price by the job. “Mr. Smith, for $xxxx per year, I can provide you with year-round tax planning as well as complete your tax return”. It might take some time in the industry to know estimated hours to structure pricing for tax consulting, so maybe that's hourly to start with, but the returns I'd keep by the project if at all possible.
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