GST/HST on construction invoices: are the rules tripping anyone else up?

GST/HST in construction isn't as simple as just adding 13% or 15% to every invoice. There are some real quirks that catch people out:

- The holdback: HST doesn't become due on the holdback until it's actually payable, not when the main invoice goes out
- New home builds vs renovations: different rules apply
- Input Tax Credits (ITCs): are you claiming GST/HST back on all your eligible job costs?
- Quebec: dealing with QST on top of GST adds another layer

Have any of these caused you problems in QBO? Or have you developed a reliable process you'd like to share? We'd especially love to hear from bookkeepers and accountants who've worked out the best QBO setup for construction HST.