The modelling assumes 100% tariff reduction and 25% of non-tariff barriers removed (32.5% in business/ICT, chemicals and cars).
assets.publishing.service.gov.uk/government/upl…
As this was a TTIP estimate, it also assumes these barriers are reduced across the entire EU.
Gains of UK-US FTA now likely to be lower or net-negative b'cos deep US FTA requires hard Brexit.