On last year's TurboTax-filed tax return, my total depreciation from form 4562 doesn't match the depreciation reported on Schedule C. Why?

First, make sure you're not combining depreciation and amortization. Depreciation is a reduction in cost basis, while amortization is a straight up deduction from taxable business income.

If you have a case where your expenses/depreciation exceed the business income, then once your taxable business income gets to zero, that's it. You can't deduct or depreciate any more. So if this is your case, any "unused" depreciation is carried over to the next year.

If you claimed less than 100% business use of a depreciable business asset, then that will also lower the amount of depreciation you are allowed.

This is pretty cut-and-dry depreciation on assets converted from personal use to business use as a daycare. The depreciation is nowhere near exceeding business income and the less-than-100% business use should already be factored in on the f4562 total. Yet TurboTax reported a smaller number than the f4562 number on Schedule C line 13 (for numerous past years I am now noticing).