Lisa v SIPP Higher Rate taxpayer

GavB79

I pay into Occupational Pension, then into SIPP to the point of recouping 40% tax, then into LISA, then into ISA. I can't fill an ISA at that point so don't need to worry about what comes after that.

But, I do not realistically have to worry about the LTA with my intended retirement date.

YellowStarling

I'm currently doing the same as Gav, however my age is such that I believe that I will be in breach of the current LTA (albeit using some assumption on growth, even if I do deem those assumptions to be conservative).

Therefore, I've attempted to model the tipping point where extra contributions into a SIPP becomes a sub-optimal strategy to maxing £4k net income a year into a LISA, basically as 75% of those extra SIPP contributions could all (if they were to form a post-£1m part of my lifetime income) attract 55% tax on the way out, based on current LTA rules (to be clear: I'm defining "extra" as on top of 1) my employer's contributions being maxed and 2) enough to make me fall into the BR tax bracket as my contributions are via salary sacrifice).

In other words, my strategy so far looks like this:
1) Maximise employers contributions in GPP
2) AVC via salary sacrifice into GPP and/or SIPP to maximise tax relief

Then either:
3A) Further SIPP contributions to enjoy tax relief on the way in
3B) LISA contributions from taxed income in that avoids HR income (and potentially LTA breach) taxes on the way out

Trying to calculate the point where any surplus income should be directed towards a LISA rather than a SIPP (all cash and reg savers and emergency fund aside, etc.) is playing on my mind when I feel an LTA breach is likely based on the current £1m threshold.

Note: I acknowledge there will be a personal allowance on pension withdrawals, and I've modeled this into my calculations, but I've omitted proper reference to this in this post for ease.

Back to my conundrum, I'm left thinking I need either the LTA to increase in time (possible given general inflation and the likelihood I'm not in the smallest of minorities here, but will technically be a reduction in government revenue, and has already been higher in the past so would represent a U-turn) or the income tax rates for HR and LTA breach to fall from their current 40%, 45% and 55% rates (again, not easily forecasted, if at all).

If that wasn't grey enough, all of this is then subject to inescapable assumptions made in my own estimations of investment growth, meaning what proportion of my lifetime income will even be above £1m (if any) is entirely configurable at the touch of a key, all of which points to me having to predict my destination to reverse calculate the most efficient route of getting there.

All a bit chicken and egg, but I don't know which egg will hatch the best chicken, or which chicken that egg is likely to have come from. Now I'm disappearing into analogy purgatory, so is this a case of where chucking something into a LISA is at least spreading my bets against unknown future LTA and income tax changes?